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

Example Input: The term elastic potential energy is used to describe potential energy due to an object's shape.
Example Output: What term is used to describe potential energy due to an object's shape?

Example Input: Population is an important level of organization in ecology and the unit of microevolution.
Example Output: What is an important level of organization in ecology and the unit of microevolution?

Example Input: Currently, the only known stable systems undergoing fusion are interiors of stars.
Example Output:
Currently, the only known stable systems undergoing fusion are what?