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:
Which of these reduces the need for people to use nonrenewable resources?  
 (A) recycling paper products (B) watering the lawn once a week (C) designing cars that are fuel efficient (D) using coal to generate electricity
answer:
C


question:
What is potential energy?  
 (A) The energy an object has due to its motion. (B) The energy an object has due to its position. (C) The energy that increases the mass of an object. (D) The energy that increases the temperature of an object.
answer:
B


question:
Which of these do scientists most likely do when studying the interaction of animals in their natural habitat?  
 (A) collect samples of types of trees (B) observe and record behaviors (C) conduct experiments in a laboratory (D) change environment and observe responses
answer:

B


