The incorrectly marked waterform is - D. Letter D -- Lake Tanganyika.
With the letter D, we don't have marked the Lake Tanganyika on this map, but instead, it is the Lake Victoria from where the waters of the Nile River originate. The Lake Tanganyika, on this map, is on the southwest of the Lake Victoria that is marked with the letter D, or we can also say, between the Lake Victoria and the upper Congo River.
