TASK DEFINITION: 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.
PROBLEM: Which is an example of a chemical reaction?  
 (A) Vinegar added to baking soda forms a gas. (B) Water evaporates into air. (C) Sugar dissolves in water. (D) Corn kernels are crushed to form flour.

SOLUTION: A

PROBLEM: Which energy source is considered nonrenewable?  
 (A) moving water (B) fossil fuel (C) wind (D) biomass

SOLUTION: B

PROBLEM: Sodium is a metal with one valence electron. Which of these elements has properties similar to sodium?  
 (A) magnesium (B) potassium (C) aluminum (D) calcium

SOLUTION:
B