उत्तर : 2. "ताना झील"
व्याख्या :

The Blue Nile originates at Lake Tana in Ethiopia (where it is called the Abay River). The river flows generally south before entering a canyon about 400 km (250 mi) long, about 30 km (19 mi) from Lake Tana, which is a tremendous obstacle for travel and communication between north and south Ethiopia.