River Brahmaputra forms a gorge at.

Explanation:

The Brahmaputra River carves a deep valley through Namcha Barwa mountain (7755m). The Brahmaputra River flows from the Kailash Range's Chemayungdung glacier near Mansarovar Lake.

Final Answer: 

Hence, the correct answer is option (C) i.e.Namcha Barwa.