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

Example Input: Fermat’s principle states that light will always take the path of the least amount of time.
Example Output: Fermat’s principle states that light will always take the path of least amount of?

Example Input: Some plants have stolons, or stems, that run along the ground and are commonly called runners.
Example Output: Some plants have stolons, or stems, that run along the ground and are commonly called what?

Example Input: Mechanical waves term describes waves that travel through matter.
Example Output:
What term describes waves that travel through matter?