Explanation:

- Gregory King is often credited with being one of the earliest people to attempt estimating national income. He created a social table estimating the income distribution in England in 1688.

- Simon Kuznets is known for developing a comprehensive system of national income accounting in the 20th century and was awarded the Nobel Prize in Economics for his work.

- J.M. Keynes contributed significantly to macroeconomic theory and policy but is not directly credited with the creation of national income accounting.

- Prof. D.R. Gadgill was an Indian economist known for his work in planning and developing economic policies in India, not national income accounting.

Correct Answer: Option 4 - Gregory King.