No, the nominative plural is spelled полотенца. You can find a declension table here

In Russian 'мой' (also моя and моё) means 'my' and used only when talking about on certain object - Мой кот - my cat Моя тарелка - my plate Моё имя - my name (имя is an exeption, all words ending with -мя are neuter, usually neuter words end with -о, like место (place) or -e like солнце (sun)).

In your sentance мой is masculine singular, but полотенца is neuter plural.

Мои is used with all plural objects asking what? with some exeptions

No, полотенца is plural so it needs a plural possessive noun.

It would be "моё полотенце" since "towel" is a neuter noun.

I wrote this and was told i had a typo, should have been marked as a mistake. Typo should not be an option for multiple choice questions.

No, мои полотенца because полотенца is plural