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 the following is the best example of potential energy?  
 (A) a fallen rock (B) a burning match (C) a liter of gasoline (D) a red-hot piece of iron

Ex Output:
C


Ex Input:
Which of these best describes wind energy?  
 (A) limited (B) renewable (C) damaging (D) inexpensive

Ex Output:
B


Ex Input:
Which weather instrument measures air pressure?  
 (A) thermometer (B) anemometer (C) rain gauge (D) barometer

Ex Output:

D