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]: Prolonged exercise stimulates muscle cells to absorb sugar from the blood. This mechanism reduces stress placed on the body by signaling the body to produce  
 (A) insulin. (B) lipids. (C) hemoglobin. (D) hydrochloric acid.
[EX A]: A

[EX Q]: You wish to closely observe a small insect. Which tool is the best to use?  
 (A) a balance (B) a test tube (C) a telescope (D) a magnifying glass
[EX A]: D

[EX Q]: How are light and sound similar?  
 (A) They both travel at the same speed. (B) They are both waves. (C) They are both electromagnetic. (D) They both travel through a vacuum.
[EX A]:
B