The main clause here is The man autographed copies of it at the bookstore. This means that the subordinate clause is what is left - who wrote this new and popular book.
The subordinate clause functions as an adjective, which means that it describes the subject <em>the man. </em>
Confidently would be the adverb in the sentence because it is describing the verb spoke.
Answer: "adjective" .
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Jim is nervous about going to the dance <span>because he does not want to dance with women there. Dancing with women is kinda awkward and embarrassing if you are not used to it. He doesn't want to be viewed as "bad."</span>
Just because it reduces harm to the ecosystem does not mean it is environmentally sound.