b) The most famous river that flows north is also the longest river in the world: the Nile, which passes through 11 different countries in northeastern Africa.
a) Its principal tributaries are the White Nile and the Blue Nile.
c) The former is the stretch of river that begins at Lake No in South Sudan, while the latter is the stretch of river that begins at Lake Tana in Ethiopia.
d) Then these two tributaries meet in Sudan, near the capital city of Khartoum, and then flow north through Egypt to the Mediterranean Sea.
