The correct answer is: a) The Namgyal Dynasty.
The Namgyal Dynasty was a Tibetan Buddhist dynasty that ruled Sikkim from 1642 to 1975. The dynasty was founded by Phuntsog Namgyal, who was invited by the Sikkimese people to rule their country. The Namgyals were responsible for building many of Sikkim’s most important heritage sites, including the Enchey Monastery, the Tashichho Dzong, and the Namgyal Institute of Tibetology.
British colonial rule had a significant impact on Sikkim, but it did not lead to the construction of any major heritage sites. The Indian government has also been involved in the preservation of Sikkim’s heritage, but it has not been the primary patron of these sites. International NGOs have also played a role in the preservation of Sikkim’s heritage, but they have not been as significant as the Namgyal Dynasty.
The Namgyal Dynasty was a powerful and influential dynasty that ruled Sikkim for over 300 years. They were responsible for building many of Sikkim’s most important heritage sites, and their legacy continues to be felt in Sikkim today.