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.
--------
Question: Two atoms of oxygen combine to form pure oxygen gas. What is the electrical charge of the O_{2} molecules?  
 (A) positive (B) negative (C) neutral (D) variable

Answer: C


Question: A class made a solar cooker out of a large can. What color should they paint the can in order to collect the most heat?  
 (A) black (B) green (C) pink (D) white

Answer: A


Question: Scientists have observed an increase in global temperatures over the past 100 years. Which phenomena do scientists believe contributes to the increase in temperatures?  
 (A) an increase in undersea volcanic activity (B) a decrease in the distance between Earth and the Sun (C) an increase in certain gases released during the use of fossil fuels (D) a decrease in the amount of water on Earth due to overconsumption

Answer:
C