Which interrogative pronoun best completes the sentence?
how is the pronoun used?

will dad ask to take the first piece of freshly fried fish?

a.
who; subject

b.
whose; possessive

c.
whom; object of a preposition

d.
whom; direct object

Interrogative pronouns are pronouns that are used to introduce a sentence. These pronouns don't have antecedents because their antecedents are unknown.  The interrogative pronoun that best completes the sentence above and how it is used is: whom and used as a direct object. The correct answer is option D.