Final answer:
The Himalayan mountains had a critical impact on ancient Indian civilization by providing water for crops, which supported agriculture and enabled the Harappan civilization to flourish in the Indus Valley. The correct option is c.
Step-by-step explanation:
The impact of the Himalayan mountains on ancient Indian civilization was primarily their role in providing water for crops.
The Indus River, originating from the Himalayas, provided fertile plains crucial for agriculture, thus supporting the development of the Harappan civilization. This early civilization benefited from the natural irrigation and fertile land, allowing them to grow crops such as cotton, peas, and barley.
Furthermore, the abundance of water enabled the Harappans to master urban planning, including building sophisticated water resource systems. While the Himalayas may have offered some protection from invasion, their most direct and significant impact was the provision of a consistent and ample water supply that enabled large-scale agriculture and sustained urban life.
Hence, Option c is correct.