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]: Living things are classified as producers or consumers according to  
 (A) their speed of movement (B) the size of their communities (C) how they obtain food (D) how they reproduce
[EX A]: C

[EX Q]: A dish of sugar water was left on a window sill. One week later, there were only sugar crystals left in the dish. The water was gone. The best explanation for the appearance of sugar crystals is  
 (A) some of the water was absorbed by the dish. (B) the air condensed. (C) the light shining on the window sill produced more sugar. (D) the water evaporated.
[EX A]: D

[EX Q]: Some classrooms have computers. The computer is most useful to the students because it helps them  
 (A) play games. (B) watch movies. (C) listen to music. (D) find information.
[EX A]:
D