The President of India National Congress as the time of partition of i India was

J. B. Kripalani (Acharya Kripalani) was the President of the Indian National Congress during the crucial period of 1946–1947 and held the office at the time of India’s partition and independence on 15 August 1947. Authoritative biographical sources note his election as Congress president in 1946 and describe his controversial tenure through the independence period, including friction with other leaders over party–government relations [1]. Contemporary lists and summaries of Congress leadership likewise record Kripalani as party president at the time of partition, specifying his term around Nov 1946–Dec 1947 [2]. Thus, option 2 (J. B. Kripalani) is correct.

Sources

1. [1] https://www.britannica.com/biography/Jivatram-Bhagwandas-Kripalani
2. [2] https://en.wikipedia.org/wiki/J._B._Kripalani