They are valued metals unlike the paper bills today which is given the value in the hands of the government and are just printed. Gold and silver also have all the main components that money should have, portability, limited supply, durability, divisibility, uniformity, and so on.
The correct answer is A
The last great west African empire fell
Songhai empire is arguably the greatest Sudanese empire to have risen. the empire was at its height during the reign on its founder Soni Ali, and controlled the Tran-saharan trade all the way along the Niger. its invasion,coming in a time of several civil wars led to its downfall.
In those times, tribes in West Africa are very vulnerable. They lived in villages with little to no defense at all. The citizens just litter the place and they can easily be abducted. All that the West African slavers got to do is to burn the huts where the poor citizens hide so they can lure them out and then capture them using crude nets often dressed with sharp metal hooks to stop resistance.