Answer : 2. "कल्याण अर्थशास्त्र"
Explanation :

Explain: -For Welfare Economics and Social Choice Theory, Amartya Sen, in 1998 was awarded the Noble Prize. Welfare economics is a branch of economics that uses microeconomic techniques to evaluate well-being (welfare) at the aggregate (economy-wide) level. ... The field of welfare economics is associated with two fundamental theorems.