In the Trans-African slave trade, other things were traded besides human cargo. The Arab nations along the Mediterranean Sea and the tribal nations of Sub-Saharan Africa were dependent on each other for the commodities of gold and salt Which BEST describes why these two regions were dependent on each other?

A)They both disliked the Europeans, and because of that only traded with
each other

B) They shared a common religion and that made each region highly
dependent on the other

C) They each had one of the commodities but not the other, so they needed
their trading partner to provide it

D) They each had a surplus of those commodities, so the easiest thing to do
was to give that surplus to the other one.

The obvious explanation on why the Arab nations along the Mediterranean Sea and the tribal nations of Sub-Saharan Africa were dependent on each other for the commodities of gold and salt is that "They each had one of the commodities but not the other, so they needed their trading partner to provide it."

While the Arab nations along the Mediterranean Sea have the expertise and resources to mine salt, they do not have resources to mine gold, yet they place much value on it. Sub-Saharan Africa on the other hand have the resources and expertise to mine gold, but not salt, which they also need for many purposes including preservation, therefore, the two regions needed trading partners to provide it.