Concept: Trade between southern and northern Nigeria involves the exchange of region-specific products.
Explanation:The southern part of Nigeria is known for producing cash and food crops such as plantains, cassava (used to make garri), kolanuts, and palm oil.
These goods are transported from the south to the markets in the north.
Products like beef, onions, groundnuts, and grains are mainly produced in the north and sent southwards, not the other way round.
Answer: B. plantains, garri, kolanuts and palmoil