The correct answer is B. 30.
The population density of Chhattisgarh in 2001 was 144 per square kilometer. The population density of Chhattisgarh in 2011 was 174 per square kilometer. The increase in population density is 30 per square kilometer.
Option A is incorrect because the population density of Chhattisgarh in 2001 was 144 per square kilometer, not 125 per square kilometer.
Option C is incorrect because the population density of Chhattisgarh in 2001 was 144 per square kilometer, not 135 per square kilometer.
Option D is incorrect because the population density of Chhattisgarh in 2001 was 144 per square kilometer, not 145 per square kilometer.
Option E is incorrect because the population density of Chhattisgarh in 2001 was 144 per square kilometer, not 155 per square kilometer.