Explanation:

These were a series of meetings in three sessions called by the British government to consider the future constitution of India.
The conference resulted from a review of the Government of India Act of 1919, undertaken in 1927 by the Simon Commission, whose report was published in 1930.
The first session had 73 representatives, from all Indian states and all parties except the Indian National Congress, which was waging a civil disobedience campaign against the government.
Its principal achievement was an insistence on parliamentarianism—an acceptance by all, including the princes, of the federal principle—and on dominion status as the goal of constitutional development.
The second session was attended by Mahatma Gandhi as the Congress representative; it failed to reach agreement, either constitutionally or on communal representation.
The third session was shorter and less important, with neither the Congress nor the British Labour Party attending.
The result of these deliberations was the Government of India Act, 1935, establishing provincial autonomy and also a federal system that was never implemented.