我国下列地理分界线，经过阴山山脉的是[ ]

A、地势二、三阶梯分界线

B、800毫米等降水量线

C、季风区与非季风区分界线 

D、亚热带与暖温带分界线

During storm conditions on a ship，the mooring tensions should be adjusted so that（）.

A.all mooring lines have a different tension

B.the leeward lines have higher tension than the windward lines

C.the maximum tension of the most heavily loaded line does not exceed the safe working load

D.all horizontal tension forces on the windward lines are no greater than the vertical tension forces