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.

[EX Q]: The cells of a plant help the plant maintain its life functions. What part of a plant cell has the function of producing sugar in the presence of sunlight?  
 (A) chloroplast (B) cytoplasm (C) mitochondria (D) nucleus
[EX A]: A

[EX Q]: Why does the leaf of a plant look green?  
 (A) Because it absorbs green light (B) Because it reflects green light (C) Because it absorbs only yellow and blue light (D) Because it reflects a mixture of yellow and blue light
[EX A]: B

[EX Q]: Why do some animals hibernate in the winter?  
 (A) to find food for their young (B) to adapt to environmental changes (C) to attract a mate (D) to avoid predators
[EX A]:
B