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 correctly arranges three scientific terms-theory, law, and hypothesis-from least to most accepted or tested?  
 (A) theory, hypothesis, law (B) hypothesis, law, theory (C) theory, law, hypothesis (D) hypothesis, theory, law

Ex Output:
D


Ex Input:
The fusion reaction that fuels the Sun converts hydrogen into  
 (A) carbon. (B) iron. (C) neon. (D) helium.

Ex Output:
D


Ex Input:
What does the mechanical energy of a system include?  
 (A) the sum of the potential and kinetic energy (B) the difference of the potential and kinetic energy (C) only the kinetic energy (D) only the potential energy

Ex Output:

A