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]: 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
[A]: C


[Q]: 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
[A]: A


[Q]: The energy that allows the water cycle to occur comes from  
 (A) friction. (B) electricity. (C) the Sun. (D) radioactive decay.
[A]:
C