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]: Most of the United States is a part of which tectonic plate?  
 (A) Pacific Plate (B) Eurasian Plate (C) North American Plate (D) South American Plate
[A]: C


[Q]: Which two protein molecules are essential for muscle contraction and relaxation?  
 (A) actin and myosin (B) collagen and tubulin (C) hemoglobin and myoglobin (D) amylase and polymerase
[A]: A


[Q]: Rocks can be classified many different ways, including as igneous, metamorphic, and sedimentary. This classification is based on the  
 (A) origin of the rocks. (B) use of the rocks. (C) size of the rocks. (D) hardness of the rocks.
[A]:
A