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

Ex Input:
Plankton is the most common life form in the ocean.

Ex Output:
What is the most common life form in the ocean?

Ex Input:
In machines that increase force, such as ramps and doorknobs and nutcrackers, output is greater is the relation between output and input force.

Ex Output:
In machines that increase force, such as ramps and doorknobs and nutcrackers, what is the relation between output and input force?

Ex Input:
The fact that water in a reservoir is elevated above the ground means that it has potential kind of energy.

Ex Output:
The fact that water in a reservoir is elevated above the ground means that it has what kind of energy?