How to rename my subcategory

Hi there,`

Is there a conditional function that would rename the option value ‘select subcategory’ if a specific term selected?

there is the php code that display the subcategory:

echo '<br /><span id="sub_cats">';
if(!empty($cat[1]->term_id))
{
$args2 = "orderby=name&order=ASC&hide_empty=0&parent=".$cat[0]->term_id;
$sub_terms2 = get_terms( 'auction_cat', $args2 );
$ret = '<select class="do_input" name="subcat">';
$ret .= '<option value="">'.__('Select Subcategory','AuctionTheme'). '</option>';
$selected1 = $cat[1]->term_id;
foreach ( $sub_terms2 as $sub_term2 )
{
$sub_id2 = $sub_term2->term_id;
$ret .= '<option '.($selected1 == $sub_id2 ? "selected='selected'" : " " ).' value="'.$sub_id2.'">'.$sub_term2->name.'</option>';
}
$ret .= "</select>";
echo $ret;																																				}
echo '</span>';

In human readable format, I was expecting to do something like this:

If University category selected, rename ‘select subcategory’ to ‘select grades’

Any help will be appreciated, Thanks in advance