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

Water can be boiled to kill giardia and most other pathogens.
Water can be boiled to kill giardia and most other what?

Fermat’s principle states that light will always take the path of the least amount of time.
Fermat’s principle states that light will always take the path of least amount of?

Mercury is the smallest planet in our solar system.

What is the smallest planet in our solar system?