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

Superior sagittal sinus is the largest of the sinuses.
What is the largest of the sinuses?

Water affects the availability of oxygen important element in aquatic environments and in flooded soils.
Water affects the availability of what important element in aquatic environments and in flooded soils?

Coal can be mined from earth and used as an energy source.

Which of these can be mined from Earth and used as an energy source?