Do not apply special price to options

Hi.

i would like to have a special price for my products using the special tab in the admin product page but i do not want the discount to also apply to the options on the product page.

the price for the item is $20 and i made the special price $15 than i see that all the prices for the options were reduced by 25% and marked in red near the old price crossed off

i cannot find any extension for this so i would like to change the code, i think the file that needs to be modified is system/library/cart.php

please help me with this, i am using OC 1.5.6.4

thank you

This shouldn't happen by default. Are you sure you aren't running a mod like Options Boost? That mod actually adds code to discount the option and it can be disabled by following the steps in the readme.