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.

[Q]: Campers shouted toward a canyon wall. What characteristic of sound best explains why the campers heard an echo?
(A) Sound waves traveled slowly down the canyon. (B) Sound waves were absorbed by the canyon wall. (C) Sound waves reflected off the canyon wall. (D) Sound waves were refracted around the canyon.
[A]: C

[Q]: When microorganisms deplete the oxygen in soil through respiration, the soil becomes
(A) humus. (B) anaerobic. (C) compost. (D) aerobic.
[A]: B

[Q]: Which statement best explains why the force of a hurricane diminishes as the hurricane moves over land?
(A) A high pressure area develops. (B) The sea level rises on the coast. (C) The winds start to spin clockwise. (D) The supply of warm, moist air decreases.
[A]:
D