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

Ex Input:
Most protein antigens require signals from helper t cells (th2) to proceed to make antibody.

Ex Output:
Most protein antigens require signals from helper t cells (th2) to proceed to make what?


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:
Circannual behavioral rhythms are linked to the yearly cycle of seasons.

Ex Output:

What type of behavioral rhythms are linked to the yearly cycle of seasons?