As for B, it can be understood that ocean currents will affect the air above.
The air above the warm current is relatively warm and humid.
The air above the cold current is relatively cold and dry.
At the intersection of cold and warm air, the air above will also meet and form a weak front. Because the density of warm current is relatively small, it will be lifted, forming frontal cloud system and frontal fog; When warm air flows through a cold current, air cooling will also form a large area of advection fog. These two kinds of fog produced at sea are collectively called sea fog.