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: In an electric motor, electrical energy is converted into  
 (A) mechanical energy. (B) chemical energy. (C) thermal energy. (D) light energy.
Example Output: A

Example Input: Evidence of organisms that lived on Earth a long time ago would most likely be found in  
 (A) crystals. (B) lava. (C) sedimentary rock. (D) metamorphic rock.
Example Output: C

Example Input: A whistle produces a sound because blowing air in the whistle causes  
 (A) the whistle material to shake. (B) the air inside the whistle to vibrate. (C) the air to be absorbed by the whistle. (D) the air in the whistle to heat up and expand.
Example Output:
B