The establishment of Portuguese ports on the West African coast led to the decline of trans-Saharan trade. The correct option among all the options given in the question is option "B".
The main reason behind the
Trans-Saharan trade between West Africa and North Africa was actually economic
in nature. The people of the two regions were faced with different climatic
conditions and so their needs differed as well. This was one of the main reason
behind the origin of this trade route.
