Description : Sink hole is a phenomenon of _______ topography. (1) Plain (2) Desert (3) Tundra (4) Karst
Last Answer : (4) Karst Explanation: The course of a river from its source to its mouth is normally divided into 3 sections, namely upper, middle and lower courses. Action of the river on its valley from ... , the river's long profile would become a smooth, concave, graded profile from its source to mouth.