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 is an example of a form of electrical energy?  
 (A) lightning (B) windmill (C) radio waves (D) sound waves

Ex Output:
A


Ex Input:
In the human body, which system functions primarily to defend the body against disease?  
 (A) digestive (B) immune (C) nervous (D) respiratory

Ex Output:
B


Ex Input:
Which of these events have the most influence on regional climate?  
 (A) frequent tornadoes (B) ocean trade winds (C) winter snowstorms (D) temperature inversions

Ex Output:

B