Your answer is Noun, number 2. a load. This is because a cargo is like a package or shipment being shipped off somewhere, For example, like how mail is sent to a post office and delivered to the address that is says on the piece of mail but a cargo is like a package type of shipment.
While a couple of these can be used as answers to your question the most prominent one out of the bunch would be the rivers symbolizing the deep history and culture of the African people.
