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

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

Example Input: Carried through body happens if cancer cells enter the blood stream.
Example Output: What happens if cancer cells enter the blood stream?

Example Input: Work is done only if a force is exerted in the direction of motion.
Example Output:
Work is done only if a force is exerted in the direction of what?