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.
--------
Question: A light-year is a measure of  
 (A) time. (B) energy. (C) distance. (D) direction.

Answer: C


Question: During which process does a caterpillar become a butterfly?  
 (A) fertilization (B) metamorphosis (C) asexual reproduction (D) biological adaptation

Answer: B


Question: Which of the following statements best describes the role of gravity in the formation of stars?  
 (A) Gravity converts solid matter into gases and light energy. (B) Gravity causes gases and dust particles to condense into spheres. (C) Gravity cools gases and liquids until they become one solid mass. (D) Gravity pushes rocks and dust particles outward from a dense center.

Answer:
B