Question

Which sentence contains a correctly used relative pronoun A my sister, that lives in Milwaukee, is going to law school. B That assignment, which was due today was very difficult., C I knew which she would never finish the race., D My friend that wants to be a doctor is named Cameron

Answer 1

D, the first one should be who instead of that, the second one should be that instead of which, the third one should be that instead of which

Answer 2

Remember that relative pronouns are used to connect a clause or phrase to a noun or pronoun.
The answer should be....
 B. That assignment, {which] was due today was very difficult