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.

Input: Consider Input: The planets in the solar system revolve around the Sun because the Sun is  
 (A) made of hydrogen and helium. (B) older than other objects in the solar system. (C) the source of most heat and light energy. (D) the strongest source of gravity in the solar system.

Output: D


Input: Consider Input: Greta passed a comb through her hair several times. She then placed the comb next to a stream of water flowing from a faucet. Greta observed the stream of water bend toward the comb. How did passing a comb through her hair allow the comb to bend the stream of water?  
 (A) by making the comb more absorbent (B) by giving the comb an electrical charge (C) by increasing the thermal energy of the comb (D) by breaking some of the chemical bonds in the comb

Output: B


Input: Consider Input: The crust, the mantle, and the core are structures of Earth. Which description is a feature of Earth's mantle?  
 (A) contains fossil remains (B) consists of tectonic plates (C) is located at the center of Earth (D) has properties of both liquids and solids


Output: D