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

[Q]: The refrigerator door contains iron of the following statements best explains why magnets usually stick to a refrigerator door.
[A]: Which of the following statements best explains why magnets usually stick to a refrigerator door?


[Q]: Trichomoniasis is cause by a protozoa.
[A]: Trichomoniasis is cause by what type of pathogen?


[Q]: Larva is the stage between a zygote and polyp.
[A]:
What is the stage between a zygote and polyp?