The odd one out is C. Raja Gopalchari. The other three options are all Indian independence activists who also served as President of India. C. Raja Gopalchari was a lawyer and politician who served as the first Governor-General of independent India. He was a close associate of Mahatma Gandhi and Jawaharlal Nehru, and played a key role in the Indian independence movement. However, he later broke with Nehru and the Indian National Congress, and formed his own political party, the Swatantra Party. He was a strong advocate of Hindutva, and opposed the secular policies of the Indian government.
Acharya Kripalani was an Indian independence activist and politician who served as the President of the Indian National Congress from 1946 to 1947. He was a close associate of Mahatma Gandhi, and played a key role in the Indian independence movement. He was also a member of the Constituent Assembly of India, and helped to draft the Indian Constitution.
C.V. Raman was an Indian physicist who won the Nobel Prize in Physics in 1930 for his discovery of the Raman effect. He was the first Indian to win a Nobel Prize, and is considered to be one of the greatest physicists of all time.
S. Radhakrishnan was an Indian philosopher, statesman, and diplomat who served as the second President of India from 1962 to 1967. He was a leading figure in the Indian Renaissance, and is considered to be one of the greatest Indian philosophers of the 20th century.