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.

Input: Consider Input: After a star runs out of most of its hydrogen fuel, it becomes hotter and more luminous. What stage does this represent in the life cycle of a star?
(A) quasar (B) protostar (C) red giant (D) white dwarf

Output: C

Input: Consider Input: The relationship between ticks and a dog can best be described as
(A) mutualism. (B) competition. (C) parasitism. (D) commensalism.

Output: C

Input: Consider Input: Which is an example of substances reacting chemically?
(A) iron and oxygen forming rust (B) paper being cut into small pieces (C) chocolate melting in a pan (D) flour and sugar mixed together in a bowl
Output: A