The bolded word here is the BESTSELLER. This kind of complement is a direct object complement. The adjective overnight denotes to the object bestseller which is an adjective. Another adjective complements another adjective, thus, the term direct object.
Answer:
A CLAUSE WHICH DEPENDS ON OTHER CLAUSES.
Explanation:
HE WENT TO PARK<u> </u><u><em>BECAUSE HE WAS BORED.</em></u>
THE UNDERLINED WORDS ARE DEPENDENT CLAUSE.
