Question

complete the sentence with the best relative pronoun. mr. and mrs. christensen, are members of the country club, have invited us to golf with them.

Explanation:

To solve this, we analyze the sentence structure. The clause "are members of the country club" is a non - restrictive relative clause (it provides extra information about Mr. and Mrs. Christensen and is set off by commas) modifying the noun phrase "Mr. and Mrs. Christensen". For non - restrictive relative clauses referring to people, the relative pronoun "who" is used. "That" is not used in non - restrictive relative clauses, and "which" is used for things, not people.

Answer:

who