Option 1: Simon Commission - The Simon Commission was a British parliamentary committee appointed in 1927 to discuss constitutional reforms in British India. However, this option is not the earliest because it happened after the Gaya Session of Congress.
Option 2: Gaya Session of Congress - The Gaya Session of Congress took place in 1922 and was an important event in the Indian freedom struggle. This session marked a shift in the Congress` approach towards the use of mass civil disobedience as a means of achieving independence. This option is correct because it happened before the other options.
Option 3: Tripuri Session of Congress - The Tripuri Session of Congress occurred in 1939 and was a significant event in the Indian freedom struggle. It resulted in the resignation of Subhas Chandra Bose as Congress President and the subsequent formation of the Forward Bloc. This option happened after the Gaya Session of Congress.
Option 4: Gandhi-Irwin Pact - The Gandhi-Irwin Pact was signed in 1931 between Mahatma Gandhi and Lord Irwin, the Viceroy of India. It aimed to end the civil disobedience movement and secure the release of political prisoners. This option happened after the Gaya Session of Congress.
Therefore, the correct answer is