The Bardoli Satyagraha was launched on 4th February, 1928. It was a significant movement in the history of India`s struggle for independence.

Option 1: Mahatma Gandhi is a renowned leader of the Indian independence movement, known for his philosophy of nonviolence and civil disobedience. While Mahatma Gandhi was involved in several satyagrahas, he did not launch the Bardoli Satyagraha.

Option 2: Vallabhbhai Patel, also known as Sardar Patel, was the leader who actually launched the Bardoli Satyagraha. He was a prominent figure during the Indian freedom struggle and played a crucial role in the integration of princely states.

Option 3: Rajendra Prasad was a leader and the first President of independent India. While he contributed significantly to the freedom movement, he was not directly involved in the Bardoli Satyagraha.

Option 4: Kalyanji Mehta is not a prominent figure in the Indian independence movement, and there is no evidence or historical record of his involvement in the Bardoli Satyagraha.

It is important to note that the correct answer is option 2, Vallabhbhai Patel.