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]: A light-year is a measure of  
 (A) time. (B) energy. (C) distance. (D) direction.
[EX A]: C

[EX Q]: Water vapor sometimes condenses into stratus clouds that are in contact with the ground. What forms as a result of this process?  
 (A) ozone (B) methane (C) fog (D) smoke
[EX A]: C

[EX Q]: When humans move into an area, they sometimes plant grasses, flowers, or trees that are not native to the area. The non-native species sometimes choke out the native species. Which organism would most likely be harmed by a loss of native plants in the area?  
 (A) the fungi that break down dead plants (B) the beetles that eat a variety of grass roots (C) the mosquitoes that hide under plant leaves (D) the caterpillars that eat only one type of plant
[EX A]:
D