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: Kim lost her hammer outside. When she found it a few months later, some parts of the metal were covered with flaky, brown rust. Which type of change occurred when rust formed on the hammer?  
 (A) chemical (B) electrical (C) thermal (D) physical

Answer: A


Question: Early scientists most likely saw a discharge of electricity for the first time when observing a  
 (A) waterfall (B) rainbow (C) lightning storm (D) volcano erupting

Answer: C


Question: The average temperature of the surface of Earth has increased approximately 1°C in the past century. Which reason best explains this increase in temperature?  
 (A) higher levels of oxygen in the atmosphere (B) lower levels of ozone in the atmosphere (C) higher levels of carbon dioxide in the atmosphere (D) lower levels of nitrogen in the atmosphere

Answer:
C