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.
I would say at once hope this helped
Girl I’m not writing an essay for you so start typing sis
Answer: C. First, choose a design.
Dude its either C or D but make your best guess bud all the best! I just had my opinion of this being my answer. Im pretty sure its correct.