The correct answer is: d) All of the above.
Goecha La Trek, Dzongri Trek, and Sandakphu Trek are all popular trekking routes in Sikkim. They offer stunning views of the Himalayas, including Mount Everest, Kanchenjunga, and Makalu. The Goecha La Trek is a challenging trek that takes 8-10 days to complete. It starts in the town of Lachen and ends at the Goecha La pass, which is at an altitude of 5,400 meters. The Dzongri Trek is a shorter trek that takes 5-7 days to complete. It starts in the town of Yuksom and ends at the Dzongri pass, which is at an altitude of 4,500 meters. The Sandakphu Trek is a moderate trek that takes 6-8 days to complete. It starts in the town of Darjeeling and ends at the Sandakphu peak, which is at an altitude of 3,636 meters.
All three treks offer stunning views of the Himalayas and are a great way to experience the natural beauty of Sikkim.