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]: Which of the following is the best observation of the refraction of light?  
 (A) Looking at oneself in a mirror (B) Looking at a shadow of an object (C) Viewing an object through an open window (D) Viewing an object partially in water
[EX A]: D

[EX Q]: What is the function of the nucleus in a cell?  
 (A) provides energy (B) provides nutrients (C) controls activity (D) controls movement
[EX A]: C

[EX Q]: Paleontologists often find and study the remains of ancient plants and animals. When the remains of ancient plants and animals are covered by layers of sediment over time, the remains  
 (A) melt (B) dissolve (C) become a fossil (D) evaporate into vapor
[EX A]:
C