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.

Ex Input:
Which of the following happens in our solar system?  
 (A) Earth revolves around the sun once per day. (B) The moon revolves around Earth once per day. (C) Earth revolves around the sun once per year. (D) The moon revolves around Earth once per year.

Ex Output:
C


Ex Input:
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

Ex Output:
A


Ex Input:
Which is the first step in a design process?  
 (A) Revise the solution. (B) Describe the problem. (C) Test the possible solutions. (D) Identify possible solutions.

Ex Output:

B