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

In science, something that always applies under the same conditions is called a scientific law.
In science, what do you call something that always applies under the same conditions?

Poles parts of the planet does solar energy have difficulty reaching.
What parts of the planet does solar energy have difficulty reaching?

The vast majority of fish reproduce sexually.
How do the vast majority of fish reproduce?