若线路导线的自重比载为32.33×10-3N/（m．mm）2，高温时的应力为52N/mm2，操作过电压工况时的应力为60N/mm2，某塔的水平档距为400m，高温时垂直档距为300m，则该塔操作过电压工况时的垂直档距为多少米（）？

A.450m

B.400m

C.300m

D.285m

（）the captain said is reasonable.

A.That

B.It

C.Which

D.What