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: When the cardboard cone of a radio speaker vibrates, it produces a sound in the air around it. The cone produces this sound by transferring which of the following to the air around it?  
 (A) heat (B) current (C) wave motion (D) magnetic force
Example Output: C

Example Input: Genes are located on chromosomes which are composed of  
 (A) DNA. (B) RNA. (C) ATP. (D) ADP.
Example Output: A

Example Input: Seismic waves occur as a result of an earthquake. Which statement describes a wave property that makes it possible for scientists to locate the source of an earthquake?  
 (A) The wavelength of a wave is measured from crest to crest. (B) Waves travel uniformly outward from the wave source. (C) The frequency of waves varies in different mediums. (D) Waves move at the same speed in different materials.
Example Output:
B