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.

Example Input: Some birds fly south in the fall and return in the spring. This is an example of  
 (A) migration (B) camouflage (C) hibernation (D) growth
Example Output: A

Example Input: Jeannie put her soccer ball on the ground on the side of a hill. What force acted on the soccer ball to make it roll down the hill?  
 (A) gravity (B) electricity (C) friction (D) magnetism
Example Output: A

Example Input: Why is the ozone content of the stratosphere important to living organisms?  
 (A) Ozone absorbs infrared radiation from the Sun. (B) Ozone absorbs ultraviolet radiation from the Sun. (C) Ozone is necessary to create oxygen for living things. (D) Ozone in the atmosphere prevents radiation of heat from Earth.
Example Output:
B