Which word descibes a plant's response to its environment?

-Tropism

-gravity

I would say tropism because plants can’t respond to their environment by controlling gravity!

If the squirrels were separate species, they would not be able to mate and create offsprings. Different species either can't create offsprings at all, or they cannot create an offspring that can sexually reproduce with other members of either species. Either they will create an offspring if placed together and being the same species, or they will not create it.