Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Input: Consider Input: The refrigerator door contains iron of the following statements best explains why magnets usually stick to a refrigerator door.

Output: Which of the following statements best explains why magnets usually stick to a refrigerator door?


Input: Consider Input: Platelets blood component serves both structural and molecular functions in blood clotting.

Output: What blood component serves both structural and molecular functions in blood clotting?


Input: Consider Input: Acid rain may be caused by air pollution.


Output: Acid rain may be caused by what?