What was the most impactful trade route you learned about? Explain the importance of it.

The images show two different fronts.which fronts are shown? item a shows a cold front, and item b shows a warm front.item a shows an occluded front, and item b shows a cold front.item a shows a warm front, and item b shows a stationary front.item a shows a stationary front, and item b shows an occluded front.