Prepositional phrase in the sentence they took young Marco with them?

The prepositional phrase in the sentence "They took young Marco with them" is "with them".

Here's why:

* Preposition: "with" is the preposition.

* Object of the Preposition: "them" is the object of the preposition.

* Function: The phrase "with them" acts as an adverbial phrase, modifying the verb "took" by telling us where Marco was taken.