The correct answer is option 3, Maulana Azad.

Option 1, Jawaharlal Nehru, was an important leader of the Indian National Congress, but he was not the Congress President during 1940-46.

Option 2, Sardar Vallabhbhai Patel, was also a prominent leader of the Congress, but he served as the Congress President in 1931 and 1934.

Option 4, Rajendra Prasad, was the President of India after independence, but he was not the Congress President during this specific period of 1940-46.

Maulana Azad, who was a prominent freedom fighter and scholar, served as the Congress President during 1940-46. He played a crucial role in the Quit India Movement and was a close associate of Mahatma Gandhi.