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.

[Q]: 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.
[A]: B


[Q]: What part of the digestive system first causes chemical changes to food?  
 (A) teeth in the mouth (B) saliva in the mouth (C) enzymes in the stomach (D) enzymes in the small intestine
[A]: B


[Q]: Earth's core consists primarily of iron. Which observation about another planet would provide some evidence that the planet has an iron core?   
 (A) the presence of a fluid mantle (B) the presence of Van Allen belts (C) the presence of gravitational force (D) the presence of water in three states
[A]:
B