Which of the following is an example of a prepositional phrase?

A prepositional phrase consists of a preposition followed by a noun or pronoun that serves as the object of that preposition, along with any modifiers. In this context, "on the table" is the example of a prepositional phrase. Here, "on" is the preposition, and "the table" acts as the object of the preposition, conveying a specific location.

The other options do not fit the structure of a prepositional phrase. "Quickly" is an adverb and does not include a preposition or object, while "a dog" is a noun phrase lacking a preposition entirely. "And" and "but" are coordinating conjunctions used to connect words or groups of words, therefore, they do not form a prepositional phrase either. Thus, “on the table” is the only correct answer in this instance.