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:
About how long is a lunar cycle?  
 (A) 1 day (B) 1 week (C) 28 days (D) 52 weeks

Ex Output:
C


Ex Input:
A light year is used to measure  
 (A) time. (B) distance. (C) luminosity. (D) temperature.

Ex Output:
B


Ex Input:
Which event is an example of a chemical change?  
 (A) fog rising off a river (B) wood burning in a fireplace (C) ice cream melting in the sunshine (D) grinding peppercorn into pepper flakes

Ex Output:

B