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 meeting of scientists, called a symposium, occurs every year to share recent research about the atmosphere of Earth. This symposium mainly serves which purpose in science?  
 (A) to test research methods used by other scientists (B) to develop questions about space research (C) to discuss the meaning of new discoveries (D) to explain gas properties to the general public
[EX A]: C

[EX Q]: The systems of the human body work together. Which system works with the skeletal system by pulling on the bones to create movement?  
 (A) digestive (B) circulatory (C) muscular (D) nervous
[EX A]: C

[EX Q]: Species are classified based on their characteristics. Which characteristic identifies two organisms as members of one species? The organisms  
 (A) can produce fertile offspring. (B) can communicate easily. (C) will defend their territory. (D) will move from place to place.
[EX A]:
A