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]: A student is asked to bring something that feels rough to class. Which would be BEST for him to bring?  
 (A) Pillow (B) Marble (C) Sandpaper (D) Trading card
[EX A]: C

[EX Q]: Which plant is grown for food?  
 (A) Rice (B) Tobacco (C) Orchid (D) Cotton
[EX A]: A

[EX Q]: Which of the following statements best explains why stars appear to move across Earth's sky each night?  
 (A) Earth rotates on its axis. (B) The stars orbit each other. (C) Earth revolves around the Sun. (D) The stars rotate with the Moon.
[EX A]:
A