What is the prepositional phrase in environmental art alive on Great Plains.?

The prepositional phrase in the sentence "environmental art alive on Great Plains" is "on Great Plains".

Here's why:

* Prepositional phrases start with a preposition (like "on," "in," "at," "by," etc.) and include the object of the preposition.

* "On" is the preposition, and "Great Plains" is the object of the preposition.

The prepositional phrase tells us where the environmental art is alive.