Step 1: Understanding the Concept:
"Purna Swaraj" means "Complete Independence."
Initially, the Indian National Congress (INC) sought "Dominion Status," which meant self-rule within the British Empire (similar to Canada or Australia).
However, by the late 1920s, disillusionment with British promises led the Congress to demand absolute sovereignty.
Step 2: Detailed Explanation:
The Lahore Session of the INC was held in December 1929.
Jawaharlal Nehru was elected as the President of this session, representing the radical youth wing of the party.
On the banks of the Ravi River, the Congress passed the historic "Purna Swaraj" resolution, declaring that the goal of the freedom struggle was now total independence.
Following this:
1. The tricolor flag was hoisted for the first time as a symbol of freedom.
2. January 26, 1930, was designated as "First Independence Day."
3. The session authorized the Working Committee to launch a Civil Disobedience Movement, which led to the Salt Satyagraha (Dandi March) in 1930.
Reviewing other options:
(A) Surat 1907: Known for the "Surat Split" where Moderates and Extremists parted ways.
(C) Karachi 1931: Presided over by Sardar Patel; it endorsed the Gandhi-Irwin Pact and passed resolutions on Fundamental Rights.
(D) Lucknow 1916: Famous for the "Lucknow Pact" between the INC and the Muslim League.
Step 3: Final Answer:
The Lahore Session of 1929 under Jawaharlal Nehru's presidency was the milestone event where the demand for Complete Independence (Purna Swaraj) was officially adopted.
Thus, option (B) is the correct answer.