The correct option is A Lahore session held in 1929
The Purna Swaraj declaration (or complete self-rule independent of the British Empire) was promulgated by the Indian National Congress on 19 December 1929 in its Lahore session. 26th January 1930 was declared as Purna Swaraj Diwas. At this session, it was decided that Round Table Conference was to be boycotted and Civil Disobedience was to be launched.