The ultimate base level is
A) a drainage divide.
B) a dam.
C) sea level.
D) dependent on the geological substrate.

Question

Quizplus · Accepted Answer

The ultimate base level is the lowest point to which a river can erode its channel. It is usually determined by the level of a large body of water into which the river flows, such as the ocean or a lake. As sea level is the lowest point on the earth's surface, it serves as the ultimate base level for most rivers.

The Ultimate Base Level Is