The correct economist associated with the WTO draft document is A.K. Sen. Let`s examine each option:

1. A.K. Sen: Amartya Sen is a renowned economist known for his work in welfare economics, social choice theory, economic and social justice, among others. He was indeed involved with the WTO draft document. That makes this option correct.

2. T.N. Srinivasan: He was an important economist and academic from India. He made substantial contributions to development economics and trade theory, but there`s no record of his involvement with the WTO draft document.

3. J.N. Bhagwati: Jagdish Natwarlal Bhagwati is a prominent economist, who has written a lot on international trade and globalization. He wasn`t, however, involved with drafting the WTO document.

4. Avinash Dixit: He is a well-known microeconomist, recognized for the Dixit-Stiglitz model. Again, no connection can be found between him and the WTO draft document.

So, when examined, while all these economists made significant contributions to the field, only A.K. Sen was associated with the WTO draft document.