Explanation:

- The Oudh Kisan Sabha was established to address the issues of farmers in the region of Oudh, which is part of present-day Uttar Pradesh.

- Option 1: 1918

- This year was significant post-World War I, but it doesn't align with the founding year of the Oudh Kisan Sabha.

- Option 2: 1920

- A pivotal year for agricultural movements in India, as various peasant organizations were gaining momentum.

- Option 3: 1921

- The Oudh Kisan Sabha was actually set up in this year. ??

- Option 4: 1924

- This is later than when the Sabha was founded and does not correspond with its establishment.

Option 3: 1921 is the correct answer as the Oudh Kisan Sabha was established this year. .