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.
--------
Question: 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.

Answer: C


Question: Which of these elements is found in the greatest amount in organisms?  
 (A) carbon (B) iron (C) lead (D) neon

Answer: A


Question: Modern submarines have advanced atmosphere-control systems that enable submarine crews to stay below the surface of the ocean for months at a time. Which of the following also benefits from this technology?  
 (A) architectural design (B) pollution control (C) fire prevention (D) space exploration

Answer:
D