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

Ex Input:
In pupa stage of their life cycle do insects begin developing their wings.

Ex Output:
In what stage of their life cycle do insects begin developing their wings?


Ex Input:
Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as embryos.

Ex Output:
Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as what?


Ex Input:
Friction force is caused by microscopic bumps, lumps, and imperfections colliding.

Ex Output:

What force is caused by microscopic bumps, lumps, and imperfections colliding?