This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Numbers of variable regions on each light and heavy chain of an antibody ? 
Select and explain. 
A. 1, B. 2, C. 3, D. 4
A: 1
Answer: A: 1 
Explanation: Ans. is 'a' i.e., 1