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 express the amount of energy in food?  
 (A) Calorie (B) degree Celsius (C) milliliter (D) gram
[EX A]: A

[EX Q]: Compared to Earth, the Moon is  
 (A) drier. (B) larger. (C) heavier. (D) brighter.
[EX A]: A

[EX Q]: Which of these activities makes the MOST air pollution?  
 (A) Storing trash bags (B) Reusing trash bags (C) Burning trash bags (D) Recycling trash bags
[EX A]:
C