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

Example Input: A fewer predators is most likely to cause the number of rabbits living in an area to increase.
Example Output: Which factor is most likely to cause the number of rabbits living in an area to increase?

Example Input: Photoautotrophs and chemoautotrophs are two basic types of autotrophs.
Example Output: Photoautotrophs and chemoautotrophs are two basic types of what?

Example Input: Expansion of a gas into a vacuum is irreversible because the external pressure is measurably less than the internal pressure of the gas, and no states of equilibrium exist.
Example Output:
Expansion of a gas into a vacuum is irreversible because the external pressure is measurably less than the internal pressure of the gas, and no states of what exist?