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.

Example Input: Prolonged exercise stimulates muscle cells to absorb sugar from the blood. This mechanism reduces stress placed on the body by signaling the body to produce  
 (A) insulin. (B) lipids. (C) hemoglobin. (D) hydrochloric acid.
Example Output: A

Example Input: Which unit of measurement describes an object's length?  
 (A) meter (B) kilogram (C) liter (D) degree
Example Output: A

Example Input: What direction is the movement of the energy in a food web?  
 (A) consumer to producer (B) producer to consumer (C) decomposer to producer (D) decomposer to consumer
Example Output:
B