Definition: You are given a question on clinical knowledge. You are also given 4 answer options (associated with "A", "B", "C", "D"), out of which only one is correct. You need to answer the question by selecting the correct option. You should only answer with the choice letter, not the whole answer.
Input: The two principal contractile proteins found in skeletal muscle are:
(A)actin and troponin. (B)actin and myosin. (C)troponin and tropomyosin. (D)myosin and tropomyosin.

B