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

Example Input: The frequency of a wave is the reciprocal of the period of the wave.
Example Output: The frequency of a wave is the reciprocal of what other attribute of the wave?

Example Input: A change of season and less food usually cause certain animals to migrate.
Example Output: Which two environmental changes usually cause certain animals to migrate?

Example Input: The metallic bond is responsible for the properties of metals.
Example Output:
What is responsible for the properties of metals?