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


question:
During which season of the year would a rabbit's fur be thickest?  
 (A) fall (B) spring (C) summer (D) winter
answer:
D


question:
Before strip mining for coal, the topsoil in the area is removed and stored. After mining operations are completed, the land is leveled and topsoil is replaced. The purpose of replacing topsoil is  
 (A) to prevent wind from weathering and eroding surface coal. (B) to prevent radioactive elements from polluting water sources. (C) to provide an environment for new coal formation. (D) to restore the area to a natural condition.
answer:

D