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 Input:
Which of these will best separate a saltwater solution?  
 (A) using a paper filtering system (B) using chromatography (C) allowing the salt to settle (D) allowing the water to evaporate

Ex Output:
D


Ex Input:
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

Ex Output:
A


Ex Input:
What is the liquid layer of Earth that lies beneath the mantle?  
 (A) inner core (B) outer core (C) mesosphere (D) asthenosphere

Ex Output:

B