Who among the following former Prime Ministers of India ,never served as Chief minister of Indian state?

Q. Who among the following former Prime Ministers of India ,never served as Chief minister of Indian state?
Answer: Chandra Shekhar
Notes: Chandra Shekhar Singh served as the eighth Prime Minister of India, between 10 November 1990 and 21 June 1991 before which he never served as chief minister of any Indian state.