Definition: In this task, you are given a question and answer options for that question. Using this information, you have to classify each text into different topics: medicine, nursery, psychology, chemistry, pharmacology, biology.
Input: Question: Which of the following layers must pass through the sperm to reach the egg during fertilization? 
 Options:  <0> Endometrial zone <1> Pellucid zone. <2> Striated area. <3> Sticky zone <4> Myometrial zone.
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
pharmacology