Among the following, which was the least populated state in 2011?

The correct option is Sikkim.

According to the 2011 Census of India, Sikkim was the least populated state in India. Here is a breakdown of the population details for the states mentioned in the options to help understand the comparison:

1. Sikkim: The population was approximately 6.10 lakh (610,577), making it the least populated state in the country.
2. Tripura: The population was approximately 36.74 lakh (3,673,917).
3. Haryana: The population was approximately 2.54 crore (25,351,462).
4. Jharkhand: The population was approximately 3.30 crore (32,988,134).

Comparing these figures, Sikkim has the smallest population among the given choices, as well as among all Indian states in the 2011 Census.