Q:

Magento which Catalog Block is used to display custom options?

i add new fields into custom options template like.

i add Details field following http://magento.ikantam.com/qa/how-add-custom-attributes-custom-options tutorial.
i want to Display the Details field value on Product View page. Like in this tutorial say for display the values to front side rewrite 'Mage_Catalog_Block_Product_View_Options_Type_Select' this class but is not working.
Thanks 
in this function i add "firstmenu" class into ul tag
public function getValuesHtml()
{
    $_option = $this->getOption();
    $configValue = $this->getProduct()->getPreconfiguredValues()->getData('options/' . $_option->getId());
    $store = $this->getProduct()->getStore();

    if ($_option->getType() == Mage_Catalog_Model_Product_Option::OPTION_TYPE_DROP_DOWN
        || $_option->getType() == Mage_Catalog_Model_Product_Option::OPTION_TYPE_MULTIPLE) {
        $require = ($_option->getIsRequire()) ? ' required-entry' : '';
        $extraParams = '';
        $select = $this->getLayout()->createBlock('core/html_select')
            ->setData(array(
                'id' => 'select_'.$_option->getId(),
                'class' => $require.' product-custom-option'
            ));
        if ($_option->getType() == Mage_Catalog_Model_Product_Option::OPTION_TYPE_DROP_DOWN) {
            $select->setName('options['.$_option->getid().']')
                ->addOption('', $this->__('-- Please Select --'));
        } else {
            $select->setName('options['.$_option->getid().'][]');
            $select->setClass('multiselect'.$require.' product-custom-option');
        }
        foreach ($_option->getValues() as $_value) {
            $priceStr = $this->_formatPrice(array(
                'is_percent'    => ($_value->getPriceType() == 'percent'),
                'pricing_value' => $_value->getPrice(($_value->getPriceType() == 'percent'))
            ), false);
            $select->addOption(
                $_value->getOptionTypeId(),
                $_value->getTitle() . ' ' . $priceStr . '',
                array('price' => $this->helper('core')->currencyByStore($_value->getPrice(true), $store, false))
            );
        }
        if ($_option->getType() == Mage_Catalog_Model_Product_Option::OPTION_TYPE_MULTIPLE) {
            $extraParams = ' multiple="multiple"';
        }
        if (!$this->getSkipJsReloadPrice()) {
            $extraParams .= ' onchange="opConfig.reloadPrice()"';
        }
        $select->setExtraParams($extraParams);

        if ($configValue) {
            $select->setValue($configValue);
        }

        return $select->getHtml();
    }

    if ($_option->getType() == Mage_Catalog_Model_Product_Option::OPTION_TYPE_RADIO
        || $_option->getType() == Mage_Catalog_Model_Product_Option::OPTION_TYPE_CHECKBOX
        ) {
        $selectHtml = '<ul id="options-'.$_option->getId().'-list" class="firstmenu options-list">';
        $require = ($_option->getIsRequire()) ? ' validate-one-required-by-name' : '';
        $arraySign = '';
        switch ($_option->getType()) {
            case Mage_Catalog_Model_Product_Option::OPTION_TYPE_RADIO:
                $type = 'radio';
                $class = 'radio';
                if (!$_option->getIsRequire()) {
                    $selectHtml .= '<li><input type="radio" id="options_' . $_option->getId() . '" class="'
                        . $class . ' product-custom-option" name="options[' . $_option->getId() . ']"'
                        . ($this->getSkipJsReloadPrice() ? '' : ' onclick="opConfig.reloadPrice()"')
                        . ' value="" checked="checked" /><span class="label"><label for="options_'
                        . $_option->getId() . '">' . $this->__('None') . '</label></span></li>';
                }
                break;
            case Mage_Catalog_Model_Product_Option::OPTION_TYPE_CHECKBOX:
                $type = 'checkbox';
                $class = 'checkbox';
                $arraySign = '[]';
                break;
        }
        $count = 1;
        foreach ($_option->getValues() as $_value) {
            $count++;

            $priceStr = $this->_formatPrice(array(
                'is_percent'    => ($_value->getPriceType() == 'percent'),
                'pricing_value' => $_value->getPrice($_value->getPriceType() == 'percent')
            ));

            $htmlValue = $_value->getOptionTypeId();
            if ($arraySign) {
                $checked = (is_array($configValue) && in_array($htmlValue, $configValue)) ? 'checked' : '';
            } else {
                $checked = $configValue == $htmlValue ? 'checked' : '';
            }

            $selectHtml .= '<li>' . '<input type="' . $type . '" class="' . $class . ' ' . $require
                . ' product-custom-option"'
                . ($this->getSkipJsReloadPrice() ? '' : ' onclick="opConfig.reloadPrice()"')
                . ' name="options[' . $_option->getId() . ']' . $arraySign . '" id="options_' . $_option->getId()
                . '_' . $count . '" value="' . $htmlValue . '" ' . $checked . ' price="'
                . $this->helper('core')->currencyByStore($_value->getPrice(true), $store, false) . '" />'
                . '<span class="label"><label for="options_' . $_option->getId() . '_' . $count . '">'
                . $_value->getTitle() . ' ' . $priceStr . '</label></span>';
            if ($_option->getIsRequire()) {
                $selectHtml .= '<script type="text/javascript">' . '$(\'options_' . $_option->getId() . '_'
                . $count . '\').advaiceContainer = \'options-' . $_option->getId() . '-container\';'
                . '$(\'options_' . $_option->getId() . '_' . $count
                . '\').callbackFunction = \'validateOptionsCallback\';' . '</script>';
            }
            $selectHtml .= '</li>';
        }
        $selectHtml .= '</ul>';

        return $selectHtml;
    }
}

A:

Basically this block  section is Mage_Adminhtml_Block_Catalog_Product_Edit_Tab_Options_Type_Select
and your blog template file of this block is 
app/design/adminhtml/default/default/template/ikantam/catalog/product/edit/options/type/select.phtml and it code may like 
app/design/adminhtml/default/default/template//catalog/product/edit/options/type/select.phtml.

As per as your question upgradation :
block:
Mage_Catalog_Block_Product_View_Options_Type_Select it rendered  the  details ta product page  and it template file is
template:
app\design\frontend\YourPackage\YourTemplate\template\catalog\product\view\options\type\select.phtml

