instruction:
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:
Question: They produce myelin in the central nervous system: 
 Options:  <0> Astrocytes <1> Ependymal cells. <2> Satellite cells. <3> Schwann cells. <4> Oligodendrocytes
answer:
biology


question:
Question: The simultaneous expression of IgM and IgD is observed for the first time in lymphocytes: 
 Options:  <0> Early Pro-B. <1> B mature. <2> Late Pro-B. <3> Pre-B. <4> B immature
answer:
biology


question:
Question: To calculate the number of different genotypes in any allelic series the formula is applied: 
 Options:  <0> (n-1) / 2. <1> n x (n + 1) / 2. <2> n x (n-1) / 2. <3> (n-1) x (n + 1) / 2. <4> (2n-1) / 2.
answer:

biology