Which one among the following States of India has the lowest density of population?

Answer: (c) Arunachal Pradesh

Arunachal has India’s lowest density (~17 per km²).

The idea

Population density is population divided by area, commonly expressed as people per square kilometre. Rugged mountains, forests and limited cultivable land can keep average density low. For this 2007 question, the relevant completed census was 2001; later density figures should be labelled separately.

Why the others are wrong

(a) Himachal ~123 per km² (2011).

(b) Meghalaya ~132.

(d) Sikkim ~86.

Also know

A State-wide average hides dense valley settlements and sparsely inhabited uplands. Density differs from the population growth rate, which measures change over time. As of Census 2011, Arunachal Pradesh had about 17 people per square kilometre; that is a later reference, not the figure available for the 2007 exam.