The Himalayan rivers receive water both from the monsoon and snow-melt and, therefore, are perennial in nature, i.e., water flows throughout the year in these rivers. So, statement (a) stands incorrect. The peninsular rivers have been flowing in one of the oldest plateaus of the world and have reached maturity and almost their base level (vertical down-cutting is negligible). The Himalayan rivers depict all the three stages (i.e., youth, mature and old) of the normal cycle of erosion.