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]: Which unit is used to indicate the amount of energy in food?  
 (A) ounce (B) degree (C) calorie (D) gram
[EX A]: C

[EX Q]: In the United States, which is responsible for ensuring the safety of the country's drinking water?  
 (A) Environmental Protection Agency (EPA) (B) Food and Drug Administration (FDA) (C) National Oceanic and Atmospheric Administration (NOAA) (D) Center for Disease Control (CDC)
[EX A]: A

[EX Q]: The molecule ATP is composed of elements commonly found in organic molecules. Which of the following is one of these elements?  
 (A) aluminum (B) calcium (C) phosphorus (D) tin
[EX A]:
C