Question

What is the adverb in this sentence People say that the pastry chef bakes pies perfectly.

Answer 1

Perfectly. An adverb modifies a verb and usually ends in "ly"
The verb is "bakes" and the "perfectly" describes the quality of (modifies) the baking, so it is the adverb. 
Hope that makes sense :)

Answer 2

Answer:

PERFECTLY

Explanation:

Adverbs are words that modify, describe or give further detail of adjectives, verb or other adverbs. They give information of when, where, how, in what way, in what degree, to what extend or why something happens, and many of them has the "-ly" ending. In the sentence, "perfectly" is the adverb because it modifies the verb "bakes" by providing information about the way (how) the pastry chef bakes pies.