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: 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

Answer: D


Question: Large amounts of industrial gases are released into the atmosphere every day. What happens to those gases?  
 (A) They are broken down by ultraviolet light from the Sun. (B) They are converted into nitrogen and oxygen. (C) They rise through the atmosphere and go into outer space. (D) They remain in the atmosphere for long periods of time.

Answer: D


Question: A screwdriver is used to pry the lid off a paint can. The resistance arm is 0.5 centimeters. The effort arm is 20 centimeters. What is the mechanical advantage of the screwdriver?  
 (A) 0.025 (B) 10 (C) 19.5 (D) 40

Answer:
D