Instructions: 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: Physical features help animals survive. Which statement best describes physical adaptations that occur through natural selection in changing environments?
(A) They result in population decline. (B) They are all observable in the fossil record. (C) They occur slowly over long periods of time. (D) They are more likely to be observed in plants.
Output:
C