Correct option is A
For historical context:
- Chittaranjan Das was the President of the Indian National Congress for the 1922 Gaya session.
- Hakim Ajmal Khan served as the Congress president but not specifically for a Gaya session.
- Mahatma Gandhi, while a prominent leader within the Congress, did not serve as its president during the Gaya session.
Given the information, (a) Chittaranjan Das, considering the historical context of Congress sessions during the early 20th century.