TASK DEFINITION: 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.
PROBLEM: Which of the following happens in our solar system?  
 (A) Earth revolves around the sun once per day. (B) The moon revolves around Earth once per day. (C) Earth revolves around the sun once per year. (D) The moon revolves around Earth once per year.

SOLUTION: C

PROBLEM: Which body systems are most involved in the response when someone stubs his or her toe?  
 (A) nervous and muscle (B) muscle and endocrine (C) nervous and digestive (D) reproductive and circulatory

SOLUTION: A

PROBLEM: Which equation summarizes the process of respiration?  
 (A) water + carbon dioxide + energy -> sugar + oxygen (B) oxygen + sugar -> carbon dioxide + water + energy (C) carbon dioxide + oxygen + water -> sugar + energy (D) sugar + carbon dioxide + energy -> oxygen + water

SOLUTION:
B