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]: What is the most common element in a star such as the Sun?  
 (A) helium (B) oxygen (C) nitrogen (D) hydrogen
[A]: D


[Q]: An animal has six legs. What is it most likely to be?  
 (A) a spider (B) a fly (C) a lizard (D) a centipede
[A]: B


[Q]: One similarity between a small, solid sample of aluminum and a large, liquid sample of aluminum is that both samples have  
 (A) a definite shape. (B) a definite volume. (C) the same number of atoms. (D) the same amount of energy.
[A]:
B