Definition: You are given a science question (hard-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: The kinetic energies of particles in a sample of matter are increasing. This sample is most likely
(A) a liquid that is warming. (B) a gas that is cooling. (C) a liquid that is turning into a solid. (D) a gas that is turning into a liquid.
Output:
A