Answer:
southwest
Explanation:
You want to know the direction of prevailing winds at Trondheim, Norway.
The winds in the area of the Atlantic Ocean and north of the "horse latitudes" are generally from the west. The direction is modified somewhat, and may be reversed, by various landforms in the area around the southern ends of Greenland and Alaska.
Winds in the area of Norway are generally parallel to the coast on the Norwegian Sea, so are from the southwest.