This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Introduction and gametogenesis., Subject name: Anatomy
When does a secondary oocyte complete its second meiotic division to become a mature ovum? 
Select and explain. 
A. At ovulation, B. Before ovulation, C. At feilization, D. At pubey
C: At feilization
Answer: C: At feilization 
Explanation: Secondary oocyte complete its second meiotic division to become a mature ovum at feilization. At ovulation, a secondary oocyte begins meiosis II, but this division is arrested at metaphase. The secondary oocyte will remain arrested in metaphase until a sperm penetrates it at feilization. Therefore, the term "mature ovum'" is somewhat of a misnomer because it is a secondary oocyte that is feilized, and, once feilized, the new diploid cell is known as a zygote. If feilization does not occur, the secondary oocyte degenerates.