Where does a stream typically have its greatest discharge? a. at its headwaters b. where the gradient is steepest c. at its mouth d. at a junction with a tributary

The correct answer is - C. at its mouth.

The discharge of a stream or a river is the greatest at their mouth. The reason for this is that their flow ends up at their mouth, their waters are not allowed to move further because of the bigger body of water in which they enter, so the waters slow down significantly. Because the water slows down significantly the stream or the river lose their power so they are not able to keep moving the sediments that they carry with them, they start depositing them thus resulting in their biggest discharge. Because of this depositions lot of interesting and attractive features are formed close to the mouth of the river.