The correct option is
1 only
Explanation
The Brahmaputra river system is one of the largest in the world. It originates from the Chemayungdung glacier in the Kailash range near the Mansarovar lake. Its course traverses three countries: China (Tibet), India, and Bangladesh, exhibiting distinct characteristics in each region due to varying topography and climatic conditions.
Statement-wise Analysis:
- Statement 1 is Correct: In Tibet, the river is known as the Tsangpo. It flows eastward longitudinally for a considerable distance, running parallel to the Greater Himalayas. This stretch is located in southern Tibet.
- Statement 2 is Incorrect: The river does not enter India through a wide plain. Instead, on reaching Namcha Barwa (7757 m), it takes a sharp U-turn and cuts a deep gorge known as the Dihang Gorge to enter India in Arunachal Pradesh. It is here that it flows rapidly as the Dihang (Siang) before reaching the plains.
- Statement 3 is Incorrect: The characteristics of the river are contrary to the statement. In Tibet, the river passes through a cold and dry area; consequently, it carries a smaller volume of water and less silt. Due to the flat terrain of the Tibetan Plateau, the river has a gentle gradient and is navigable (relatively calm) for about 640 km. In contrast, once it enters India, it passes through a region of high rainfall. Here, the river carries a large volume of water and a considerable amount of silt, making it prone to flooding and forming a braided channel in the Assam valley.
Key Takeaway: The Brahmaputra flows as a sluggish, navigable river in the dry, flat Tibetan plateau (Tsangpo) but transforms into a voluminous, braided, and flood-prone river upon entering the high-rainfall region of India through a deep gorge.