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 galaxy is the Milky Way?  
 (A) spiral (B) elliptical (C) irregular (D) oval

Ex Output:
A


Ex Input:
A scientific guess about the cause and effect of an event is called  
 (A) a variable. (B) a theory. (C) a hypothesis. (D) an observation.

Ex Output:
C


Ex Input:
Which instrument would be best for measuring the volume of a pebble?  
 (A) metric ruler (B) stopwatch (C) triple beam balance (D) graduated cylinder

Ex Output:

D