The correct answer is: a) Nyingma tradition of Buddhism.
Dubdi Monastery is a Buddhist monastery in Sikkim, India. It is considered to be the oldest monastery in Sikkim and is associated with the Nyingma tradition of Buddhism. The monastery was founded in the 17th century by Ngawang Namgyal, the first Chogyal of Sikkim. It is located in the village of Dubdi, about 10 kilometers from Gangtok, the capital of Sikkim.
The Nyingma tradition is the oldest of the four major schools of Tibetan Buddhism. It is said to have been founded by Padmasambhava, an Indian Buddhist master who is also known as Guru Rinpoche. The Nyingma tradition emphasizes the importance of meditation and the practice of tantra.
The Kagyu tradition is one of the four major schools of Tibetan Buddhism. It was founded by Marpa Lotsawa, a 11th-century Tibetan translator who studied with the Indian master Naropa. The Kagyu tradition emphasizes the importance of lineage and the practice of Vajrayana Buddhism.
The Sakya tradition is one of the four major schools of Tibetan Buddhism. It was founded by Khon Konchog Gyalpo, a 10th-century Tibetan master. The Sakya tradition emphasizes the importance of logic and debate.
The Gelug tradition is one of the four major schools of Tibetan Buddhism. It was founded by Tsongkhapa, a 14th-century Tibetan master. The Gelug tradition emphasizes the importance of monastic discipline and the study of sutras.