TASK DEFINITION: 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.
PROBLEM: The Sun is classified as a star. Which characteristic identifies the Sun as a star?  
 (A) The Sun spins on its axis. (B) The Sun is located outside the Milky Way galaxy. (C) The Sun is part of the Big Dipper. (D) The Sun produces light and energy in a nuclear reaction.

SOLUTION: D

PROBLEM: An infectious disease causes an increase in the body temperature and a decrease in the blood glucose levels of a deer. What is most likely an effect of this disease?  
 (A) a disruption in the homeostasis of the deer (B) a change in the genetic makeup of the deer (C) an increase in the energy level of the deer (D) an increase in the reproductive rate of the deer

SOLUTION: A

PROBLEM: After a soccer game, Brittany sat under a fan because she was hot. Under the fan, she felt cooler than before. Which explains why Brittany felt cooler under the fan?  
 (A) Air moving under the fan is cooler than air that is still. (B) The evaporation of sweat absorbs heat from the skin. (C) Water vapor from the fan condenses on the skin. (D) The fan speeds convection currents in the air.

SOLUTION:
B