The correct answer is (b), Uttar Pradesh.
Uttar Pradesh is the most populous state in India, with a population of 200.3 million in 2011. It has a population density of 828 people per square kilometer, which is the highest of any state in India.
Bihar is the second most populous state in India, with a population of 103.8 million in 2011. It has a population density of 1,102 people per square kilometer.
Maharashtra is the third most populous state in India, with a population of 112.3 million in 2011. It has a population density of 377 people per square kilometer.
West Bengal is the fourth most populous state in India, with a population of 91.3 million in 2011. It has a population density of 880 people per square kilometer.
The population density of a state is calculated by dividing the population of the state by the area of the state. The population density of Uttar Pradesh is higher than the population density of Bihar, Maharashtra, and West Bengal because Uttar Pradesh has a larger population and a smaller area than these states.