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 important use of coal is to produce energy for homes. Coal can be burned and converted to  
 (A) wind energy. (B) nuclear energy. (C) electrical energy. (D) solar energy.

Answer: C


Question: A delta at the mouth of a river is the direct result of  
 (A) runoff from sewage. (B) deposition of sediment. (C) an ancient glacier that passed through. (D) an underground river flowing to the ocean.

Answer: B


Question: The smallest part of an element that retains the properties of the element is the  
 (A) proton. (B) nucleus. (C) electron. (D) atom.

Answer:
D