Question

How is the underlined pronoun used in the sentence?

Who is your all-time favorite comedian?

a. direct object

b. object of a preposition

c. subject

Answer 1

a. direct object

Direct objects are words or set of words or phrases that are directly or is in contact immediate to its describer, either a noun pronoun adjective or adverb.
For example,
1.A. Direct Object
Sally brought Cindy yellow -daisies- to cheer her up.