Assertion:  The ecological sustainability of the Indira Gandhi Canal Project has been questioned by various scholars. 
Reasoning:  Their point of view has also largely been validated by the course of development this region has taken during the last four decades, which has resulted in the degradation of the physical environment.

Both Assertion (A) and reasoning (R) are correct, and R is the correct explanation of A.

The ecological sustainability of the Indira Gandhi Canal Project has been questioned by various scholars. Their point of view has also largely been validated by the course of development this region has taken during the last four decades, which has resulted in the degradation of the physical environment. It is a hard fact that attaining sustainable development in the command area requires major thrust upon the measures to achieve ecological sustainability.