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: Which process in the water cycle returns water from the surface of Earth to the atmosphere?  
 (A) condensation (B) evaporation (C) precipitation (D) runoff
Example Output: B

Example Input: Which characteristic of frogs is an adaptation to living in water?  
 (A) strong legs (B) webbed feet (C) dull colors (D) moist skin
Example Output: B

Example Input: When entire communities in an ecosystem change over time, it is known as  
 (A) migration. (B) extinction. (C) overpopulation. (D) ecological succession.
Example Output:
D