Turn the given fact into a question by a simple rearrangement of words. This typically involves replacing some part of the given fact with a WH word. For example, replacing the subject of the provided fact with the word "what" can form a valid question. Don't be creative! You just need to rearrange the words to turn the fact into a question - easy! Don't just randomly remove a word from the given fact to form a question. Remember that your question must evaluate scientific understanding. Pick a word or a phrase in the given fact to be the correct answer, then make the rest of the question. You can also form a question without any WH words. For example, "A radio converts electricity into?"

Fact: Active immunity results when an immune response to a pathogen produces the basis of immunological memory.
Active immunity results when an immune response to a pathogen produces the basis of what?

Fact: hot flashes can occur when menstruation stops occurring.
What can happen when menstruation stops?

Fact: A rainbow is formed by the bending of light.

What is formed by the bending of light?