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: A star is a large astronomical body that  
 (A) reflects light. (B) condenses light. (C) emits light. (D) absorbs light.
Example Output: C

Example Input: When microorganisms deplete the oxygen in soil through respiration, the soil becomes  
 (A) humus. (B) anaerobic. (C) compost. (D) aerobic.
Example Output: B

Example Input: How do muscles and bones work together to create body movement?  
 (A) The muscles pull on the bones. (B) The muscles protect the bones. (C) Muscles grow at the same rate as bones. (D) Muscles send electrical impulses to bones.
Example Output:
A