Instructions: 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: When a transverse wave passes from right to left through a medium, what happens to the particles of the medium?
(A) Particles travel from right to left along the wave. (B) Particles travel from left to right along the wave. (C) Particles move back and forth parallel to the wave. (D) Particles move back and forth perpendicular to the wave.
Output:
D