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]: The phases of the Moon are daily changes in the appearance of the Moon. One reason Moon phases occur is because the Moon reflects sunlight. Which is another reason that the phases of the Moon occur?  
 (A) Earth is tilted on the axis. (B) The Moon rises and sets. (C) The Moon orbits Earth. (D) Earth orbits the Sun.
[EX A]: C

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

[EX Q]: A company plants trees on a bare hillside. Which of these is the BEST reason for planting the trees?  
 (A) The trees provide oxygen for the soil. (B) The trees prevent soil from washing away. (C) The trees make shade for animals living there. (D) The trees cause animals to move to other places.
[EX A]:
B