单选题 At what speed was a train traveling on a trip when it had completed half of the total distance of the trip?
(1)The trip was 460 miles long and took 4 hours to complete.
(2)The train traveled at an average rate of 115 miles per hour Oil the trip.
(A) 条件(1)充分，但条件(2)不充分．
(B) 条件(2)充分，但条件(1)不充分．
(C) 条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．
(D) 条件(1)充分，条件(2)也充分．
(E) 条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．