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: In which layer of the Sun does nuclear fusion occur?  
 (A) core (B) radiative zone (C) convection zone (D) chromosphere

SOLUTION: A

PROBLEM: Which of these is not an instinctive behavior?  
 (A) a bird building a nest (B) a turtle burying its eggs (C) a bear hibernating in winter (D) a horse pulling a plow

SOLUTION: D

PROBLEM: Which upgrade to a school will most likely reduce the school's consumption of nonrenewable resources?  
 (A) solar-collection panels (B) high-speed computers (C) wireless Internet connections (D) biodegradable carpeting

SOLUTION:
A

