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

SOLUTION: D

PROBLEM: Which set contains kingdoms that contain only heterotrophs?   
 (A) Protists, Fungi (B) Bacteria, Animals (C) Plants, Fungi (D) Animals, Fungi

SOLUTION: D

PROBLEM: A student had a cup of ice while working outside. After a while, the ice melted because the Sun emits energy in the form of light and  
 (A) electricity. (B) heat. (C) magnetism. (D) sound.

SOLUTION:
B