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 of these best describes wind energy?  
 (A) limited (B) renewable (C) damaging (D) inexpensive

Answer: B


Question: Which adaptation helps a bird fly?  
 (A) larger feet (B) bigger eyes (C) longer beaks (D) hollow bones

Answer: D


Question: What causes a blue block to appear blue in the sunlight?  
 (A) The block absorbs all blue light. (B) The block bends (refracts) all blue light. (C) Only blue light is reflected by the block. (D) Only blue light passes through the block.

Answer:
C