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:
A boy pulls a sweater off over his head. His hair is attracted to the sweater due to  
 (A) a magnetic force (B) a heat transfer (C) a chemical change (D) an electrical charge

Ex Output:
D


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:
Which is the best way to generate an electrical current in a coil of wire?  
 (A) stroking the coil with a piece of silk (B) heating the coil uniformly (C) laying the coil near a magnet (D) rotating the coil in a magnetic field

Ex Output:

D