Awatershed is the valley location where a river ends the mountain area where a river starts an area of saturated soil from which water can be removed an area where all draining water goes into the same river system

an area or ridge of land that separates waters flowing to different rivers, basins, or seas.

an area where all draining water goes into the same river system

Explanation:

A watershed is an area which occupies water from the rainfall and snow melt that drains into a water body such as marshes, river , streams and groundwater. This is also called as drainage basin because of the fact that the water from many sources drains into a common outlet.

On the basis of the above description, this can be said that a watershed is an area where all draining water goes into the same river system is the correct option.