The correct answer is: All of the above.
The Teesta River is a major river in the Indian states of Sikkim, West Bengal, and Assam. It is the largest tributary of the Brahmaputra River. The Teesta River has a high volume of water, steep gradients, and year-round flow. These factors make it ideal for hydropower projects.
The Teesta River is a perennial river, meaning that it flows year-round. This is due to the fact that the river is fed by snowmelt from the Himalayas. The Teesta River also has a high volume of water. This is due to the fact that the river is fed by a number of tributaries, including the Rangit River, the Torsa River, and the Lachen River.
The Teesta River has a steep gradient. This means that the river drops quickly over a short distance. This makes the river ideal for hydropower projects, as it means that the river can be used to generate electricity with a relatively small amount of infrastructure.
The combination of high volume of water, steep gradients, and year-round flow makes the Teesta River and its tributaries ideal for hydropower projects. In fact, the Teesta River is one of the most important rivers for hydropower in India.