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: In a lab investigation, a student notes that two metal blocks have the same mass. Based on this observation, if the two blocks were put on opposite sides of a balance, they would best represent  
 (A) balanced forces. (B) unbalanced forces. (C) equal and opposite reactions. (D) objects in motion.

Output: A


Input: Consider 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

Output: C


Input: Consider Input: Which group of animals contains ONLY reptiles?  
 (A) lizard, frog, snake (B) turtle, lizard, crocodile (C) octopus, snail, turtle (D) crab, earthworm, snake


Output: B