You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

[Q]: Which two protein molecules are essential for muscle contraction and relaxation?  
 (A) actin and myosin (B) collagen and tubulin (C) hemoglobin and myoglobin (D) amylase and polymerase
[A]: A


[Q]: A pot is heated on a stove. Which process causes the metal handle of the pot to also become hot?  
 (A) combustion (B) convection (C) radiation (D) conduction
[A]: D


[Q]: The fur of the snowshoe rabbit changes to a lighter color in the winter. This allows the rabbit to blend in with its surroundings. This change is an example of  
 (A) extinction (B) competition (C) biological adaptation (D) ecological succession
[A]:
C