Which of the following statement is incorrect about the  influenza epidemic of early twentieth century?

None of the above

The correct answer is option 4: None of the above

Option 1: It killed about 5% of the total population of India at that time. Correct. The influenza epidemic of 1918–19 was extremely severe and is estimated to have killed around 5% of India's population, making it one of the deadliest demographic disasters in the country's history.

Option 2: There was a negative population growth of India during the decade of 1921-1931 due to this epidemic. Incorrect. The dates are factually incorrect. The influenza epidemic occurred in 1918–19 and affected population growth during the decade 1911–1921.

Option 3: The influenza pandemic was a global phenomenon. Correct. The epidemic was not confined to India; it was part of the worldwide influenza pandemic often referred to as the Spanish Flu, which affected many countries across the globe.