With reference to the Indus River system, of the following four rivers, three of them pour into one of them which joins the Indus direct. Among the following, which one is such a river that joins the Indus directly?

Answer: (a) Chenab

The Jhelum, Ravi and Sutlej all end in the Chenab, and the Chenab (as the Panjnad) joins the Indus.

The idea

In a river network, follow each confluence downstream instead of selecting the longest tributary. Names can change after major junctions. Here the combined lower channel is called Panjnad before it reaches the Indus; “directly” must be read within that naming convention.

Jhelum joins Chenab → Ravi also joins Chenab → Beas joins Sutlej → Sutlej meets the Chenab system → Combined channel is called Panjnad → Panjnad joins Indus near Mithankot

Why the others are wrong

(b) The Jhelum ends in the Chenab.

(c) The Ravi ends in the Chenab.

(d) The Sutlej ends in the Chenab to form the Panjnad; it does not reach the Indus on its own.

The trap

The Sutlej is the longest of the four, so it looks like the main river.

Elimination technique

Jhelum and Ravi meet Chenab before the Indus, so they cannot be the final collector. Sutlej also meets this combined system; distinguish the lower-channel name Panjnad from an independent Sutlej mouth.

Also know

The Punjab river family is Jhelum, Chenab, Ravi, Beas and Sutlej. Chandra and Bhaga form Chenab at Tandi; Beas and Sutlej meet at Harike. Zanskar and Shyok are other Indus tributaries outside this five-river set. A long river can still be a tributary of another channel.