The correct answer is B: Aug 1946. Direct Action Day was observed on August 16, 1946. This day was called by the All-India Muslim League, led by Muhammad Ali Jinnah, to assert the Muslim League's demand for a separate Muslim state (Pakistan) through peaceful protest and demonstrations. However, in Calcutta (now Kolkata), the day unfortunately degenerated into widespread communal riots and violence, leading to a tragic loss of life and massive destruction. This event further deepened the communal divide in British India.
A: July 1946 is incorrect. While significant political developments were occurring in July 1946, such as the Muslim League's withdrawal of its acceptance of the Cabinet Mission Plan, Direct Action Day itself was not observed in this month. The decision for Direct Action Day was made in July, but its implementation was scheduled for August.
C: Sept 1946 is incorrect. By September 1946, the aftermath of Direct Action Day was still being felt, and the interim government was being formed with Jawaharlal Nehru as Vice-President. The specific observance of Direct Action Day did not happen in September.
D: Oct 1946 is incorrect. October 1946 also saw ongoing communal tensions and violence in various parts of India, particularly in Noakhali. However, the specific event designated as Direct Action Day by the Muslim League was definitively on August 16, not in October.
Direct Action Day was a pivotal moment in the lead-up to the partition of British India, highlighting the growing political and communal chasm between Hindus and Muslims, ultimately accelerating the demand for Pakistan.