Which of the following correctly identifies the parts of speech in the underlined portions of the sentence: "The owner of the Labrador puppy arrived earlier than expected"?

In the sentence "The owner of the Labrador puppy arrived earlier than expected," the underlined portions consist of "Labrador" and "earlier."

"Labrador" functions as an adjective in this context, as it describes what type of puppy it is. Adjectives serve to modify nouns, and here "Labrador" provides specific information about the noun "puppy."

On the other hand, "earlier" is an adverb that modifies the verb "arrived." Adverbs typically provide information about when, how, where, or to what extent something happens, which is the case here as "earlier" indicates the timing of the arrival in relation to what was expected.

Thus, the correct identification of the parts of speech in the underlined portions is an adjective (Labrador) and an adverb (earlier).