Answer:
Shelly represents a person's name, therefore the word is a noun.
Step-by-step explanation:
Beautiful is an adjective as it describes the activity that Shelly was carrying out.
Dance is a verb. It is the action that Shelly was performing beautifully.
Thoroughly is an adverb as it modifies or qualifies the verb dance.
Captivated is a verb which describes how the audience watched the dance.
Audience is a noun that represents the people who were watching Shelly dance