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.

[EX Q]: Many types of organisms live in a meadow. With the introduction of a large, swift-moving predator into the meadow ecosystem, which group of organisms will MOST likely have an advantage of surviving and reproducing?  
 (A) mice that have the thickest fur (B) foxes that have the largest ears (C) gophers that dig the deepest holes (D) rabbits that can run the fastest
[EX A]: D

[EX Q]: The ounce, the pound, and the ton are units of  
 (A) time. (B) weight. (C) length. (D) distance.
[EX A]: B

[EX Q]: Which characteristic best identifies a pure substance?  
 (A) shape (B) texture (C) melting point (D) state of matter
[EX A]:
C