Step 1: Recall why the pact was needed.
In 1932 the British announced separate electorates for the Depressed Classes, and Gandhi began a fast in Yerwada Jail to oppose this, fearing it would split Hindu society.
Step 2: Identify who negotiated the settlement.
Dr B R Ambedkar, representing the Depressed Classes, sat down with Gandhi to work out a compromise given the pressure of the fast.
Step 3: Confirm the outcome.
They signed the Poona Pact on 24 September 1932, dropping separate electorates but increasing reserved seats for the Depressed Classes within a joint electorate.
Hence, the correct answer is option (A) Bhimrao Ambedkar and Mahatma Gandhi.