You are given a science question (hard-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.

[Q]: Which of these reduces the need for people to use nonrenewable resources?  
 (A) recycling paper products (B) watering the lawn once a week (C) designing cars that are fuel efficient (D) using coal to generate electricity
[A]: C


[Q]: Which layer of Earth is the source of lava that erupts from volcanoes?  
 (A) asthenosphere (B) inner core (C) outer core (D) lithosphere
[A]: A


[Q]: Which statement best explains why the Sun and the Moon appear to be about the same size in the sky?  
 (A) The Sun and the Moon have the same diameter. (B) The Moon is larger in diameter and farther from Earth than the Sun. (C) The Moon is smaller in diameter and is closer to Earth than the Sun. (D) The Sun and the Moon are the same distance from Earth.
[A]:
C