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: What force pulls things towards the center of Earth?  
 (A) magnetism (B) gravity (C) friction (D) energy
Example Output: B

Example Input: What tool would be used to examine a fingerprint?  
 (A) a graduated cylinder (B) a hand lens (C) a pair of goggles (D) a thermometer
Example Output: B

Example Input: Which substance is usually found in nature as a liquid, solid, and gas?  
 (A) water (B) rock (C) metal (D) glass
Example Output:
A