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?"

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

A: Active immunity results when an immune response to a pathogen produces the basis of what?
****
Q: Fact: cars can cause acid rain.

A: Emission from cars contribute to which weather phenomenon?
****
Q: Fact: A fuel source may be stored in sedimentary rock for millions of years.

A:
What may be stored in sedimentary rock for millions of years.?
****