Hint: The All-India Depressed Classes Association was organised by the same person who went on to become the chairman of the Drafting committee of the Constituent Assembly of India after the independence of India in 1947.
Complete Answer: The All-India Depressed Classes Association was an important organisation that took part in the Round Table Conferences with Lord Irwin at London. We shall take a look at the options one by one.
a.Mahatma Gandhi: Mahatma Gandhi worked for the upliftment of the depressed classes and established the Harijan Sevak Sangh in the year 1932 to eliminate the practice of untouchability in India. But he was not associated with the All-India Depressed Classes Association in India. So, it is an incorrect option.
b.Dr. B. R. Ambedkar: The All-India Depressed Classes Association was established by Dr. B. R. Ambedkar in the year 1930 to make the fair representation of the Scheduled Castes in the decision-making bodies of India. He participated in the Second Round Table Conference as a representative of this Association. So, it is the correct option.
c.Mahatma Jyotiba Phule: Jyotiba Phule was a person who worked for the upliftment of the depressed classes in India but he lived in the nineteenth century. However, since the All-India Depressed Classes Association was established in 1930, he could not be associated with this organisation by any means. So, it is an incorrect option.
d.None of these: since we already have one of the options as the correct answer, therefore this option has gone out of bounds. So, it is an incorrect option.
So, the correction answer is option b.
Note:The All-India Depressed Classes Association was involved in the meetings with Lord Irwin and demanded a provision for separate electorates in India for the depressed classes, just as it was happening with the Muslims of India after the Montague-Chelmsford Reforms of 1919.