Which sage has been associated with Rewalsar in district Mandi, Himanchal Pradesh?

The correct answer is: A. Lomas Rishi

Lomas Rishi is a Hindu sage who is said to have lived in the Rewalsar lake area in the Indian state of Himachal Pradesh. He is said to have been a disciple of the sage Vashishta and to have been the father of the sage Agastya. Lomas Rishi is also said to have been the author of the Lomas Rishi Samhita, a treatise on Hindu philosophy.

The other options are incorrect because:

• Vyas Rishi is a different Hindu sage who is said to have been the author of the Mahabharata.
• Parshuram Rishi is a different Hindu sage who is said to have been the sixth incarnation of Vishnu.
• Valmiki Rishi is a different Hindu sage who is said to have been the author of the Ramayana.

Rewalsar is a town and a municipal council in Mandi district in the Indian state of Himachal Pradesh. It is located on the banks of the Rewalsar Lake, which is a sacred lake for Hindus and Buddhists. The town is also home to a number of temples and monasteries.