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.

[Q]: Rock layers with sand-sized particles were most likely deposited by  
 (A) wind. (B) water. (C) glaciers. (D) landslides.
[A]: A


[Q]: If you breathe on a mirror, part of the mirror clouds up. What are you actually seeing when you see the mirror cloud up?  
 (A) Water droplets that formed from cooled water vapor in your breath (B) Carbon dioxide that you are breathing out from your lungs (C) Oxygen that you are breathing out from your lungs (D) Cooled nitrogen in the air around you
[A]: A


[Q]: Earth's atmosphere is made of many gases. Which gas do producers use to make food?  
 (A) oxygen (B) carbon dioxide (C) nitrogen (D) water vapor
[A]:
B