The overall set in Malacca straight is to
题型：单项选择题
问题：
The overall set in Malacca straight is to the NW, but from May to September there is a tendency for SE sets to prevail in some N and central parts.In this sentence,“set”refers to（）.
A.The direction of traffic flow
B.The direction of current
C.The direction of monsoon
D.The direction of wind