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.

Input: Consider 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

Output: C

Input: Consider Input: One type of animal hatches from an egg, breathes through gills when it is young, and mainly lives on land as an adult. Into which group is this animal classified?
(A) amphibians (B) birds (C) mammals (D) reptiles

Output: A

Input: Consider Input: A student is given a mixture of gravel and sand and instructed to separate them. Which tool should the student use to best complete this task?
(A) a scale and weights (B) a magnet (C) a sieve (D) a battery and wire
Output: C