Explanation:

The clash between Dr. B. R. Ambedkar and Mahatma Gandhi during the 2nd Round Table Conference was over the issue of separate electorates for the Dalits (Depressed Classes). Dr. Ambedkar advocated for separate electorates as a way to secure a fair representation for the Dalits in the legislative bodies, while Gandhi opposed this idea fearing that it would further divide the Hindu community. This disagreement led to the Poona Pact, where a single general electorate with reserved seats for the Depressed Classes was agreed upon as a compromise.