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 organ is made mostly of muscle?  
 (A) heart (B) lung (C) ear (D) brain

Ex Output:
A


Ex Input:
Some people carry a mutated allele of a particular gene that makes them resistant to HIV infection and AIDS. Which best describes this type of mutation?  
 (A) beneficial (B) asexual (C) harmful (D) unicellular

Ex Output:
A


Ex Input:
The longitude of a location determines which time zone it is in. Different time zones are the result of  
 (A) Earth's rotation (B) Earth's revolution (C) the Moon's rotation (D) the Moon's revolution

Ex Output:

A