The correct answer is option 4, Dr Rajendra Prasad. He was the first President of independent India. Dr Rajendra Prasad played a crucial role in the formation of the Indian Constitution and was elected as the President by the Constituent Assembly in 1950. He served two terms as the President from 1950 to 1962.

Option 1, Dr S. Radha Krishnan, was the second President of India, serving from 1962 to 1967. Option 2, J.L. Nehru, was the first Prime Minister of India. Option 3, Sardar Patel, was an important political leader during the Indian independence movement, but he did not serve as the President of India.

It is important to note that each option represents a prominent figure in Indian history, but only option 4 is the correct answer as the first President of independent India.