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.

Coal is used for generating about 53% of the electrical energy in the United States. Which of these environmental issues is directly contributed to by the burning of coal?
(A) beach erosion (B) ozone depletion (C) overfishing (D) air pollution
D