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: A hearing aid is a small device that contains an amplifier, a battery, a microphone, and a speaker. Which part of a hearing aid functions to detect sounds in the user's environment?  
 (A) the amplifier (B) the battery (C) the microphone (D) the speaker

Output: C


Input: Consider Input: The North America Nebula is named for its similarity in shape to the North American continent. It was discovered within the Milky Way by astronomer William Herschel in 1790. What was Mr. Herschel most likely observing?  
 (A) the explosion following the collapse of a star (B) a dense cluster of stars of varying magnitudes (C) meteorites as Earth passed through the tail of a comet (D) a cloud of hydrogen gas and dust where stars are born

Output: D


Input: Consider Input: A teacher demonstrates a chemical reaction. A student observes that the test tube in which the reaction occurs becomes warm. What is the source of the thermal energy generated by the reaction?  
 (A) energy stored in the reactants (B) breaking bonds of the reactants (C) kinetic energy absorbed by the reaction (D) potential energy absorbed by the reaction


Output: A