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 Q]: The moon goes through phases as it revolves around Earth. During which phase of the moon would it be possible for a solar eclipse to occur?  
 (A) new moon (B) full moon (C) waning (D) waxing
[EX A]: A

[EX Q]: Different units of measurement are more useful in some settings than in others. Which unit of measurement is most used when comparing distances within the solar system?  
 (A) the mile (B) the kilometer (C) the light year (D) the astronomical unit
[EX A]: D

[EX Q]: When a star explodes, an intensely bright object is formed. What is the name of this object?  
 (A) nova (B) red giant (C) supernova (D) white dwarf
[EX A]:
C