Explanation:

4th option is correct.
The Poona pact which was signed between Ambedkar and Mahatma Gandhi in 1934 provided for joint electorate with reservation for Harijans.
The election to these seats was to be by joint electorates. This means that all the members of the depressed classes registered in the general electoral roll in a constituency would form an electoral college which would elect a panel of four candidates belonging to the depressed classes of the reserved seats by the method of the single vote. The four members getting the highest number of votes in such primary election would be candidates for each such reserved seats by the general electorate.