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 bright object with a long tail of glowing gases is in orbit around the Sun. This object is most likely  
 (A) a planet (B) a star (C) an asteroid (D) a comet
Example Output: D

Example Input: Air is composed of many different substances. Which of the following components of air is a compound rather than an element?  
 (A) Argon, Ar (B) Oxygen, O2 (C) Water, H2O (D) Nitrogen, N2
Example Output: C

Example Input: Minerals can be identified using hardness, streak, and cleavage because  
 (A) minerals are inorganic. (B) crystal structure is too hard to determine. (C) crystal size is determined by the environment. (D) minerals have different recognizable properties.
Example Output:
D