Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

We couldn't solve the problem until our teacher arrived.

A. When our teacher arrived, we solved the problem.

B. Until our teacher arrived, we were able to solve the problem.

C. Not until we solved the problem could our teacher arrive.

D. Not until our teacher arrive could we solve the problem.