The correct option is C Gandhi's fast unto death led to a dialogue between him and Ambedkar, which came to be known as the Poona Pact.
Gandhi was against the idea of Ambedkar of having a separate constituency for the depressed classes. He fasted until Ambedkar agreed to have a dialogue with him. In the discussions that followed, they came up with the conclusion to give the depressed classes reserved seats in both provincial & central legislative councils. This series of dialogues came to be known as the Poona Pact.