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

Seismic waves prove the inner core it is solid.
What do seismic waves prove about the inner core?

Most protein antigens require signals from helper t cells (th2) to proceed to make antibody.
Most protein antigens require signals from helper t cells (th2) to proceed to make what?

Water is the main component of milk.

What is the main component of milk?