The correct answer is B. Sardar Vallabhbhai Patel.
Sardar Vallabhbhai Patel was the first Deputy Prime Minister of India and the Home Minister of India. He is also known as the Iron Man of India for his role in uniting the princely states of India into the Indian Union. He was a close associate of Mahatma Gandhi and Jawaharlal Nehru.
Kamaraj was a Chief Minister of Tamil Nadu and a senior leader of the Indian National Congress. He is known for his role in the Kamaraj Plan, which was a scheme to revitalize the Congress party.
Nehru was the first Prime Minister of India. He is known for his role in the Indian independence movement and for his leadership of India after independence.
Rajaji was a Chief Minister of Madras Presidency and a senior leader of the Indian National Congress. He is known for his role in the Quit India Movement and for his opposition to the partition of India.
Sardar Vallabhbhai Patel is known as the ‘Indian Bismarck’ because of his role in uniting the princely states of India into the Indian Union. Bismarck was a German statesman who is considered to be the architect of the unification of Germany.