Explanation:

According to the 2011 Census of India, Sikkim had the smallest population among all Indian states, with a total population of approximately $6.1 \text{ lakh}$ ($610,577$). This makes it the least populated state. Option (2) Mizoram had approximately $10.97 \text{ lakh}$ people. Option (3) Arunachal Pradesh had approximately $13.84 \text{ lakh}$ people. Option (4) Nagaland had approximately $19.79 \text{ lakh}$ people. All these options had higher populations than Sikkim in 2011.