Which sentence correctly compares the rates Bill and Kevin drove on their trips? (A) Bill drove at a rate that was 10 miles per hour slower than the rate Kevin drove. (B) Bill drove at a rate that was 10 miles per hour faster than the rate Kevin drove. (C) Bill drove at a rate that was 20 miles per hour slower than the rate Kevin drove. (D) Bill drove at a rate that was 20 miles per hour faster than the rate Kevin drove.