The correct answer is C. Amartya Sen.
Amartya Sen is an Indian economist and philosopher who won the Nobel Memorial Prize in Economic Sciences in 1998 for his work in welfare economics. He is also a leading figure in social choice theory and has written extensively on economic and social justice, famines, and human rights.
Rajachellaiah was an Indian economist who served as the Governor of the Reserve Bank of India from 1977 to 1982. He was also a member of the Planning Commission of India and the Finance Commission of India.
Rangarajan was an Indian economist who served as the Governor of the Reserve Bank of India from 1992 to 1997. He was also the Chairman of the Economic Advisory Council to the Prime Minister of India from 2004 to 2008.
K. N. Raj was an Indian economist who was a leading figure in the Indian Statistical Institute. He was also a member of the Planning Commission of India and the Finance Commission of India.
All four of these economists have made significant contributions to the field of economics. However, only Amartya Sen has won the Nobel Prize in Economic Sciences.