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]: As Earth revolves around the Sun, the number of daylight hours varies from place to place. In which location would the number of daylight hours remain constant?  
 (A) North Pole (B) Prime Meridian (C) Equator (D) Antarctica
[EX A]: C

[EX Q]: The human immunodeficiency virus (HIV) causes AIDS. The first known human cases AIDS were in Africa in the late 1950s. Since then, tens of millions of people have died from the disease, and tens of millions more people all over the world are infected. Which term best describes the disease AIDS?  
 (A) isolated cases (B) outbreak (C) epidemic (D) pandemic
[EX A]: D

[EX Q]: Which type of organism converts wastes and dead materials into nutrients that can be used by plants?  
 (A) carnivore (B) herbivore (C) decomposer (D) producer
[EX A]:
C