Answer:
D. the god Vishnu's hair
Explanation:
Confluence at Devprayag, Uttarakhand of the Alaknanda river (the source stream in hydrology because of its greater length) and the Bhagirathi river (the source stream in Hindu mythology). The headwaters of the river include: Mandakini, Nandakini, Pindar and the Dhauliganga, all tributaries of the Alaknanda