Assertion (A): Ganga Plain is the most densely populated part of India. Reason (R): Ganga is the most harnessed river of India.

Answer: (b) Both A and R are true, but R is not the correct explanation of A

Both are true, but density comes from fertile, flat alluvium and water that farming has used for thousands of years.

The idea

Dense settlement develops where land can sustain people and connect their livelihoods. Flat alluvial plains offer cultivable soil, water and easier transport. In an assertion–reason question, two accepted facts still need a separate cause-and-effect test.

Rivers deposit alluvium → Flat, well-watered land supports farming → Food supports lasting settlements → Roads and markets connect villages → Towns and services grow → Population concentrates over time

Why the others are wrong

(a) Harnessing the river is not WHY people crowd here.

(c) Rejects R. The Ganga system does feed India’s biggest canal networks — R is true, it just isn’t the cause of A.

(d) A is true — the Ganga plain is India’s most crowded region.

The trap

R is a true fact placed next to A. Ask: does harnessing the river CAUSE the crowding? The cause is the land itself.

Also know

Khadar is newer floodplain alluvium; bhangar is older alluvium on higher ground. The Yamuna, Ghaghara, Gandak and Kosi are important members of the Ganga system. Flood risk can be high even where soils support dense settlement. Population density is people per unit area, not a measure of river use.