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.

[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
[A]: C

[Q]: Which step will most likely ensure that the results of an investigation are valid?
(A) using a computer to graph results (B) verifying that results match the original hypothesis (C) comparing the results with those of other scientists (D) eliminating any results that appear to be abnormal
[A]: C

[Q]: Male barn swallow birds with symmetrically-shaped wings find mates more quickly than males with asymmetrical wing shapes. Which statement best explains the significance of symmetry in the barn swallow population?
(A) Symmetrical wings are attractive to females. (B) Symmetrical wings indicate genetic mutations. (C) Symmetrical wings indicate that males are good predators. (D) Symmetrical wings are signs that a bird is very aggressive.
[A]:
A