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: One of the main causes of acid rain is  
 (A) Waste from nuclear power plants (B) Spills from chemical manufacturing plants (C) Gases from burning fossil fuels (D) Gases from aerosol spray cans

Answer: C


Question: Which of the following was invented by Benjamin Franklin?  
 (A) bifocal lens (B) telescope lens (C) telephone (D) camera

Answer: A


Question: The driver of a car at a railroad crossing hears a change in pitch of the train whistle as the train passes by. This change in pitch is most likely due to  
 (A) the Doppler effect. (B) the Compton effect. (C) a change in medium. (D) a change in speed.

Answer:
A