Answer: Vanity
Explanation: Vanity is excessive pride in one’s achievements and / or appearance. In the passage, the protagonist grew more in love with herself and her pride is described as darkening, which means it became something negative. Vanity is considered negative while self-love and self-admiration are positive when you experience them in healthy amounts.
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.
Flashback, to give the reader backround information
(Apex)