Explanation:

- Option 1, BP Mandal: ?? Correct Answer. BP Mandal was the Chairman of the Second Backward Classes Commission in India. This commission, popularly known as the Mandal Commission, was established in 1979 to identify socially or educationally backward classes in India and recommend measures for their advancement.

- Option 2, Jyotiba Phule: Jyotiba Phule was a notable social reformer who worked towards the upliftment of marginalized communities in India during the 19th century. However, he was not related to the Second Backward Classes Commission.

- Option 3, Babu Jagjivan Ram: An influential Indian freedom fighter and politician, Babu Jagjivan Ram was not the Chairman of the Second Backward Classes Commission.

- Option 4, Bhim Rao Ambedkar: Known for being the principal architect of the Indian Constitution, Dr. Ambedkar was a champion of social justice. However, he did not chair the Second Backward Classes Commission.