Step 1: Historical fact.
The proposal of the Non-Cooperation Movement was adopted in the Nagpur Session of Congress in 1920 under Mahatma Gandhi’s leadership.
Step 2: Options analysis.
(A) Nagpur: Correct.
(B) Lahore: Wrong — famous for Purna Swaraj resolution (1929).
(C) Lucknow: 1916 session (Lucknow Pact).
(D) Karachi: 1931 (Karachi Resolution on Fundamental Rights).
Step 3: Conclusion.
Thus, the Non-Cooperation Movement was adopted in the Nagpur Session (1920).