instruction:
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.
question:
Leopard's opening chant suggests that he is  
 (A) unhappy. (B) confused. (C) confident. (D) generous.
answer:
C


question:
A ball is rolling on the ground. A force pushes the ball in the same direction that it is moving. What happens to the ball?  
 (A) It stops moving. (B) It moves slower. (C) It moves faster in the same direction it was moving. (D) It keeps moving in the same speed and direction.
answer:
C


question:
A star produces energy through a process called nuclear fusion. Which aspect of a star enables the process of fusion to occur?  
 (A) rotational speed (B) apparent brightness (C) surface temperature (D) chemical composition
answer:

D