A popular scenic lake in Sikkim is:

Dal Lake
Tsomgo Lake
Pangong Tso
Gurudongmar Lake

The correct answer is: d) Gurudongmar Lake.

Gurudongmar Lake is a high-altitude lake in the East Sikkim district of Sikkim, India. It is the second highest lake in India, after Tso Moriri. The lake is located at an elevation of 17,800 feet (5,430 m) above sea level and is surrounded by snow-capped peaks. The lake is a popular tourist destination and is known for its scenic beauty.

Dal Lake is a lake in Srinagar, the summer capital of Jammu and Kashmir, India. It is a popular tourist destination and is known for its houseboats, gardens, and Mughal-era buildings.

Tsomgo Lake, also known as Changu Lake, is a lake in East Sikkim district of Sikkim, India. It is a popular tourist destination and is known for its scenic beauty.

Pangong Tso is a lake in Ladakh, India. It is the second largest lake in India, after Wular Lake. The lake is located at an elevation of 14,270 feet (4,350 m) above sea level and is surrounded by snow-capped peaks. The lake is a popular tourist destination and is known for its scenic beauty.