Answer: 1
Explanation: uses the ellipses right
The way you know the subject of the sentence is plural is because it takes a plural verb. You can see that the subject of the sentence is <em>the ova </em>(plural for of Latin word <em>ovum</em>, <em />meaning egg cell), and the verb it takes is <em>undergo </em>(plural)<em>, </em>and not <em>undergoes, </em>which would be singular.
The correct is answer is A: The main idea of your essay
Hope this helps!
I believe you have a typo when it comes to the first option - it should be athletics, not athletic. The word athletic is an adjective, and the word athletics is a noun.
That being said, the correct answer is A. athletics. Even though this noun ends in -s, it is still singular. The rest of the options are all plural nouns.