Choose the correct alternative from the following :
Assertion (A) : In the upper course, the main work of the river is erosion.
Reason (R) : River flows swiftly in the upper course.
A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is NOT the correct explanation of A.
C. A is true but R is false.
D. A is false but R is true.
E. Both A and R are false
Answer: A . Both A and R are true and R is the correct explanation of A.
In its upper course, the river rushes down a steep slope and so flows swiftly, causing maintly erosion in this region.