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

Ex Input:
A concave lens is thicker at the edges than it is in the middle.

Ex Output:
What type of lens is thicker at the edges than it is in the middle?


Ex Input:
Population is an important level of organization in ecology and the unit of microevolution.

Ex Output:
What is an important level of organization in ecology and the unit of microevolution?


Ex Input:
Centrifuges use inertia to perform their task.

Ex Output:
Centrifuges use what to perform their task?