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.

Ex Input:
A combination of processes occurs when stars are forming. Which is one process most likely associated with the formation of new stars?   
 (A) Hydrogen in the cores of the stars is exhausted. (B) Material accumulates from stars that have died. (C) Elements in the stars such as iron undergo fusion. (D) Cores of stars become twice as massive as the Sun.

Ex Output:
B


Ex Input:
In the 17th century, Galileo proposed a hypothesis to explain how suction pumps work. Galileo's hypothesis was disproved, but later it helped Torricelli in the development of an instrument for measuring atmospheric pressure. How did Galileo's hypothesis most likely help with the development of this new technology?  
 (A) by leading Galileo to design a different technology (B) by allowing another scientist to critique Galileo's hypothesis (C) by providing evidence of the effects of atmospheric pressure (D) by inspiring another scientist to test an alternative hypothesis

Ex Output:
D


Ex Input:
A construction worker hit a solid steel wall with a sledgehammer, but the wall did not move. Part of the energy exerted by the worker  
 (A) was destroyed by the steel wall. (B) was converted into heat. (C) disappeared into the atmosphere. (D) was stopped by the hard surface.

Ex Output:

B