Question

complete the sentence with the best relative pronoun. luther, is terribly shy, will blush if he receives a compliment.

Explanation:

The sentence has a non - restrictive relative clause (the part between commas that provides extra information about Luther). For a non - restrictive relative clause referring to a person (Luther), the relative pronoun "who" is used. "Who" is used to refer to people in relative clauses, especially in non - restrictive ones where we are adding extra details about the subject.

Answer:

who