The hill station of Darjeeling, leased to the British by Sikkim, became important for:

The correct answer is: All of the above.

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). The town was founded in 1835 by the British East India Company as a summer retreat for British officials. It became an important trade center between India and Tibet, and was also used for military purposes.

Darjeeling is a popular tourist destination, known for its scenic beauty, tea plantations, and Himalayan views. The town is also home to a number of educational institutions, including the University of North Bengal.

Here is a brief explanation of each option:

• Summer retreat for British officials: Darjeeling was founded in 1835 by the British East India Company as a summer retreat for British officials. The town’s high elevation and cool climate made it a popular destination for escaping the heat of the Indian plains.
• Trade with Sikkim: Darjeeling was also an important trade center between India and Tibet. The town was located on the trade route between the two countries, and its merchants traded in a variety of goods, including tea, spices, and textiles.
• Military purposes: Darjeeling was also used for military purposes. The British built a number of military fortifications in the town, and it was used as a base for operations against the Nepalese.

I hope this helps!