The correct answer is Chittaranjan Das.
The Swaraj Party, also called Swarajya Dal, was founded in 1923 by Chittaranjan Das along with Motilal Nehru. It was formed within the Indian National Congress after some leaders disagreed with the decision to suspend the Non-Cooperation Movement.
The Swaraj Party believed in entering legislative councils set up by the British and opposing their policies from within, instead of boycotting them completely.