I wanna say D.
Sorry if I’m wrong:(
Answer:
to provide ports to the ocean
Explanation:
East Africa is a region that has several large lakes, located on the line of divergence between the Somali and Nubian plates, better known as the East African rift. These lakes are very important for the people living in the region. They are very rich in fish, so they provide lot of food. Because hey are large, they are also used for transportation and trade. There are other usages of them as well, such as the production of hydroelectric power, and providing water for irrigation of the agriculture. These lakes though are not connected to the oceans, so the ports are not providing any access to the oceans.
Until the early Proterozic there were only negligible amounts of free oxygen in the atmosphere
