instruction:
You are given a science question (easy-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:
Diseases that can be transmitted between organisms are
(A) infectious. (B) inherited. (C) environmental. (D) congenital.
answer:
A

question:
Scientists wonder how the Egyptian pyramids were built. They think that the huge blocks of stone may have been put into place by pushing them up a sloping pathway. The pathway is which type of simple machine?
(A) lever (B) pulley (C) inclined plane (D) wheel and axle
answer:
C

question:
Air is made up of many gases. Which gas is found in the greatest amount?
(A) Nitrogen (B) Oxygen (C) Carbon dioxide (D) Hydrogen
answer:
A