TASK 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.
PROBLEM: During an investigation, heat transferred from a liquid to the environment. Which pair of explanations can best account for this result?  
 (A) The temperature of the liquid increased, or the liquid became a gas. (B) The temperature of the liquid increased, or the liquid became a solid. (C) The temperature of the liquid decreased, or the liquid became a gas. (D) The temperature of the liquid decreased, or the liquid became a solid.

SOLUTION: D

PROBLEM: A chameleon can change colors to match its surroundings. This ability helps the chameleon survive because it can  
 (A) stay warm. (B) find a mate. (C) hunt for food. (D) be easily seen.

SOLUTION: C

PROBLEM: A student ran around a circular track. Which statement best describes the motion of the student while running?  
 (A) The speed was constant. (B) The velocity was constant. (C) The speed was always changing. (D) The velocity was always changing.

SOLUTION:
D