Final answer:
The correctly formed sentence with a prepositional phrase is: "Luca bought his dog Chopper new toys because Chopper ate all of his old ones," with the phrase 'because Chopper ate all of his old ones' functioning as an adverbial phrase.
Step-by-step explanation:
The correct sentence that uses a prepositional phrase properly is: "Luca bought his dog Chopper new toys because Chopper ate all of his old ones." In this sentence, the prepositional phrase is 'because Chopper ate all of his old ones,' which provides a reason for the action stated in the main clause and modifies the verb 'bought.' A prepositional phrase includes a preposition and its object and can function as an adjective or adverb, modifying a noun, verb, phrase, or even an entire clause. As stated in Chapter 12, Lesson 2, prepositional phrases typically provide additional details such as location, time, cause, and manner.