Question

What is the longest river

Answer 1

if you mean the longest river in the world, your answer would be river Nile. it's in the African Continent, it's around 6800 km long.  

Answer 2

The Nile River is the longest river in the world.

The Nile River begins is Uganda and flows 4,200 miles ( 6,700 km ) north passing through Sudan and Egypt.