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:
What type of force keeps the planets orbiting the Sun?  
 (A) gravitational (B) magnetic (C) electrical (D) nuclear

Ex Output:
A


Ex Input:
How do most fish get the oxygen they need to survive?  
 (A) They take in water and break it down into hydrogen and oxygen. (B) Using their gills, they take in oxygen that is dissolved in water. (C) They get their oxygen from the food they eat. (D) They come to the surface every few minutes to breathe air into their lungs.

Ex Output:
B


Ex Input:
Which process occurs when rocks and soil slide down a mountain?  
 (A) erosion (B) migration (C) recycling (D) maintenance

Ex Output:

A