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:
Students shake salt into a jar of water, and they shake pepper into a second jar of water. Which statement best compares the two jars?  
 (A) Only the salt and water is a mixture. (B) Only the pepper and water is a solution. (C) Both jars contain solutions. (D) Both jars contain mixtures.
answer:
D


question:
Forests have been cut and burned so that the land can be used to raise crops. Which consequence does this activity have on the atmosphere of Earth?  
 (A) It reduces the amount of carbon dioxide production. (B) It reduces the production of oxygen. (C) It decreases the greenhouse effect. (D) It decreases pollutants in the air.
answer:
B


question:
The gravitational force exerted by an object depends on its  
 (A) volume. (B) weight. (C) mass. (D) size.
answer:

C