The answer would most likely be C, because all the other options have to do with a job or manufacturer.
The words that represent verbs that would be useful in describing the purpose for a text are the following ones: Inform and define.
Cambridge dictionary defines the verbs "to inform" as "to tell someone about particular facts" and "to define" as "to say what the meaning of something is". When you are about to describe the purpose of a text, you are to inform the reader what you want to say and why you are saying it. You are giving meaning to your piece of writing.
C. NOUNS
Adverbs can modify verbs, other adverts, adjectives, and clauses.
It can be a single word or phrases or clauses. It answers one of these four questions: How? When? Where? and Why?
Your answer should be WHO.
Think of it like this: You wouldn't say "The boy it (a variant of 'which')", because it simply just sounds odd. Instead, you're wired to think "The boy, he (an unknown name, so it would be 'who')".
D. Rewriting the definition of a word in the form of a question
