What is NOT an advantage of the house-fall system when compared to a married-fall system using two of the ship’s booms? （）

A.There is a steady spotting area under the dockside block
B.Loading can be accomplished from a narrow apron without endangering the inboard boom
C.The system can be used for working the second deck of a warehouse
D.There is more accurate control of cargo drafts required to be stowed in the wings