What characteristic of the basin that feeds the congo river system affects movement in central africa?

The Congo River basin is one of the biggest basins in the world. It is a big obstacle for people to move in this part of Africa because:
- It is surrounded by mountains 
- It has enormous amount of water and rivers, and also almost daily precipitations, which makes it very hard for people to cross this part
 - It has constantly high temperatures and huge amount of moisture in the air, and that makes it hard for people to function in this conditions
- It's covered with very dense vegetation, it is a tropical rain forest, and the terrain is more often than not steep, so the movement is almost impossible
- There's lots of dangerous animals that can easily harm or kill people.  

Largely uneconomic because they provide little profit or food surplusi think so

It would be tomatoes i believe