You will be given a definition of a task first, then some input of the task.
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.

Question: In the activation of the serum complement, the assembly of the Membrane Attack Complex begins with: 
 Options:  <0> C9 <1> C5b. <2> C3a. <3> C6 <4> C8.
Output:
biology