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: Proxima Centauri is the closest star to the Sun. Which units do astronomers most often use for the distance between Earth and Proxima Centauri?  
 (A) miles (B) meters (C) light years (D) astronomical units
Example Output: C

Example Input: How do traits of animals such as ear shape, nose shape, and hair color most often get passed to offspring?  
 (A) sexual reproduction (B) asexual reproduction (C) adaptation (D) instinct
Example Output: A

Example Input: The primary function of a doorbell circuit is to convert electrical energy into  
 (A) sound. (B) motion. (C) radiant energy. (D) chemical energy.
Example Output:
A