The correct answer is: a) Darjeeling.
Darjeeling is a town in the Indian state of West Bengal. It is located in the foothills of the Himalayas, at an elevation of 2,205 metres (7,234 ft). Darjeeling is a popular tourist destination, known for its tea gardens, its views of Mount Kanchenjunga, and its colonial architecture.
The British East India Company established a presence in Darjeeling in the early 19th century. The company built a military cantonment in the town, and Darjeeling became a popular summer resort for British officials. In 1835, the British established the Darjeeling Himalayan Railway, a narrow-gauge railway that connects Darjeeling to the plains. The railway is a UNESCO World Heritage Site.
The British ruled Sikkim from 1890 to 1947. Darjeeling served as a base for British interaction with the Chogyal, the hereditary ruler of Sikkim. The British established a school for the Chogyal’s children in Darjeeling, and the Chogyal often visited the town.
After India gained independence in 1947, Sikkim became an independent country. However, India retained control of Darjeeling. In 1975, Sikkim became an Indian state. Darjeeling is now a part of the Indian state of West Bengal.
The other options are incorrect because they are not located near Sikkim. Shillong is located in the Indian state of Meghalaya. Shimla is located in the Indian state of Himachal Pradesh. Nainital is located in the Indian state of Uttarakhand.