Option 1 (1921-31): This decade is not the correct answer as it does not indicate a negative growth rate for the population of India.

Option 2 (1911-21): This decade is the correct answer because it indicates a negative growth rate for the population of India. During this period, the population of India decreased.

Option 3 (1941-51): This decade is not the correct answer as it does not indicate a negative growth rate for the population of India.

Option 4 (1931-41): This decade is not the correct answer as it does not indicate a negative growth rate for the population of India.

Therefore, option 2 (1911-21) is the correct answer as it represents a period in which the population of India recorded a negative growth rate.