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

Pheromones enable communication, which is vital for organisms like ants that live in a large community.
Pheromones enable what, which is vital for organisms like ants that live in a large community?

Evolution occurs by natural selection, a process whereby better-adapted members pass along their traits, according to darwin.
Evolution occurs by what process whereby better-adapted members pass along their traits, according to darwin?

Molecules of gas are rare in exosphere outermost region of the planet's atmosphere.
Molecules of gas are rare in what outermost region of the planet's atmosphere?