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

Q: The name of film that polyester fibers form is mylar.

A: What is the name of film that polyester fibers form?
****
Q: A fewer predators is most likely to cause the number of rabbits living in an area to increase.

A: Which factor is most likely to cause the number of rabbits living in an area to increase?
****
Q: Exons are cut out before mrna leaves the nucleus.

A:
Exons are cut out before what leaves the nucleus?
****