The 'Ganga Mata Temple' at Gangotri built by :

Correct option is C

The correct answer is (c) Amar Singh Thapa.

The Ganga Mata Temple at Gangotri, Uttarakhand, was originally built by Amar Singh Thapa, a Gorkha general and administrator during the early 19th century. It was later restored by the royal family of Jaipur. Built from white granite, the temple stands about 20 feet tall and exemplifies the Nagara style of architecture, prevalent in Northern India 

The temple is dedicated to Ganga Mata, the goddess of the River Ganga, and is considered one of the four sacred sites in the Char Dham Yatra

Amar Singh Thapa was a prominent Gorkha military leader who played a significant role in expanding the Gorkha Kingdom's influence in the Himalayan regions.

Additional Information:

Mythological Significance: According to Hindu mythology, King Bhagirath performed intense penance at this location to bring the celestial River Ganga down to earth to purify the souls of his ancestors. Pleased by his devotion, Lord Shiva released the Ganga from his matted locks, allowing her to flow here. This event is believed to have occurred at the sacred stone near the temple, known as "Bhagirath Shila."