Which of the following rivers marks the eastern-most boundary of the Himalayas?

Correct — D. The Himalayan ranges run from the Indus gorge in the west to the Brahmaputra gorge in the east, where the river swings sharply south around Namcha Barwa.

That bend is the accepted eastern limit. The hills beyond it, running down the Indo-Myanmar border, are the Purvanchal rather than the Himalayas proper.

So the eastern-most boundary is marked by the Brahmaputra, option (d).

Why the others are wrong

• (a)
  Kali — Kali is an internal divider rather than the eastern edge, separating the Kumaon Himalaya from the Nepal Himalaya.
• (b)
  Teesta — Teesta divides the Nepal Himalaya from the Assam Himalaya. It lies east of centre but well short of the end of the mountain chain.
• (c)
  Satluj — Satluj lies far to the west, marking the boundary between the Punjab Himalaya and the Kumaon Himalaya.

The Himalayas are described in two ways, and SSC draws on both.

Longitudinally they divide into the Trans-Himalaya, the Great Himalaya or Himadri, the Lesser Himalaya or Himachal, and the Shiwaliks.

Regionally, rivers cut them into four sections.

Punjab Himalaya lies between the Indus and the Satluj, Kumaon Himalaya between the Satluj and the Kali, and Nepal Himalaya between the Kali and the Teesta.

Assam Himalaya runs between the Teesta and the Dihang — the Brahmaputra's name where it enters India.

Key facts

• The Himalayas extend from the Indus in the west to the Brahmaputra in the east.
• The four regional divisions are the Punjab, Kumaon, Nepal and Assam Himalaya.
• The Brahmaputra is called the Dihang or Siang where it enters Arunachal Pradesh.

Common traps

• Choosing Teesta, which bounds a division inside the Himalayas rather than the chain itself.
• Treating the Purvanchal hills as part of the Himalayas when they lie beyond the eastern limit.

No directly related past PYQ was found.