The correct answer is: b) Buddhist monasteries.
Sikkim is a state in northeastern India that is home to a large number of Buddhist monasteries. These monasteries are important centers of religious activity and pilgrimage for Buddhists from all over the world. Some of the most famous monasteries in Sikkim include the Rumtek Monastery, the Enchey Monastery, and the Namgyal Monastery.
The Rumtek Monastery is the seat of the Karmapa, the head of the Karma Kagyu lineage of Tibetan Buddhism. The Enchey Monastery is a Nyingma monastery that is known for its beautiful architecture and its annual masked dance festival. The Namgyal Monastery is the official monastery of the Sikkimese royal family.
In addition to its Buddhist monasteries, Sikkim is also home to a number of Hindu temples. The most famous Hindu temple in Sikkim is the Tsomgo Lake Temple, which is located on the banks of Tsomgo Lake. The temple is dedicated to the Hindu god Vishnu.
Sikkim is also home to a small number of Christian churches and Muslim mosques. However, these religious institutions are not as prominent as the Buddhist monasteries and Hindu temples.
Overall, religious tourism in Sikkim centers around Buddhist monasteries. These monasteries are important centers of religious activity and pilgrimage for Buddhists from all over the world.