单选题 A certain ear increased its average speed by 5 miles per hour in each successive 5-minute interval after the first interval. If in the first 5-minute interval its average speed was 20 miles per hour, how many miles did the car travel in the third 5-minute interval?
(A) 1.0 (B) 1.5 (C) 2.0
(D) 2.5 (E) 3.0