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.

Example Input: What property is the same for each atom of an element?  
 (A) energy (B) mass number (C) atomic number (D) number of neutrons
Example Output: C

Example 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
Example Output: D

Example Input: Natural selection cannot occur without  
 (A) competition for unlimited resources. (B) gradual warming of Earth. (C) genetic variation in species. (D) asexual reproduction in species.
Example Output:
C