Which amongst the following is the largest glacier?

The correct answer is D) Siachin (Siachen). It is the longest glacier in the Karakoram and the longest non-polar glacier in the Himalayan system, at roughly 70 km. It lies in the Karakoram range in the Nubra region of Ladakh and is a central feature of the India-Pakistan dispute over the area.

• Zemu (C): It is the largest glacier of the Sikkim Himalaya and the eastern Himalaya, but it is much shorter, about 26 km, so it loses to Siachen.
• Gangotri (B): It is the source of the Bhagirathi in Uttarakhand, about 30 km long. It is famous mainly because it is a retreating glacier, not because of its size.
• Sasaini (A): It is a comparatively small valley glacier in the Karakoram and does not match Siachen in length or area.

The core concept is the glacier as a freshwater reserve. Himalayan glaciers feed the Indus, Ganga and Brahmaputra systems, so they matter for water security and for Mains answers on climate change and river basins.

Trap: Aspirants often pick Gangotri because it is the most familiar name. Check whether the question asks for length, area or a regional category, since Zemu is the largest in Sikkim while Siachen is the largest overall.