The correct answer is: b) Tribute and trade agreements.
The Namgyals were a Tibetan Buddhist dynasty that ruled the Kingdom of Bhutan from the 17th century to the 20th century. They maintained close relations with Tibet through a series of tribute and trade agreements. These agreements allowed the Namgyals to obtain essential goods and services from Tibet, such as food, livestock, and religious texts. In return, the Namgyals paid tribute to the Tibetan government and provided military assistance when needed.
The tribute and trade agreements between the Namgyals and Tibet were mutually beneficial. They allowed both countries to obtain the goods and services they needed, and they helped to maintain peace and stability on the border between Bhutan and Tibet.
The other options are incorrect because:
- Option a) is incorrect because the Namgyals and Tibet did not have frequent military conflicts. In fact, they had a very close relationship and cooperated on many issues.
- Option c) is incorrect because religious pilgrimages were not a major way that the Namgyals maintained relations with Tibet. While there were some religious pilgrimages between the two countries, they were not as important as the tribute and trade agreements.
- Option d) is incorrect because royal marriages were not a major way that the Namgyals maintained relations with Tibet. While there were some royal marriages between the two countries, they were not as important as the tribute and trade agreements.