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]: In the morning, students observed puddles of water all over the playground. What would best explain why the playground was dry in the afternoon?  
 (A) Animals drank the water. (B) The wind stopped blowing. (C) Someone dried the puddles. (D) The water evaporated during the day.
[EX A]: D

[EX Q]: In a northern state, a room used for growing plants is not allowing enough light to enter for healthy plant growth. Adding windows in walls facing which direction would best solve this problem?  
 (A) north (B) south (C) east (D) west
[EX A]: B

[EX Q]: If a single-celled organism that uses photosynthesis has its source of light removed, it will  
 (A) grow in size. (B) produce less energy. (C) divide repeatedly. (D) generate more waste.
[EX A]:
B