How did Plunkitt begin his political career?

One of the leading figures in the New York City political machine called Tammany Hall, George Washington Plunkitt has marked an unmatched place in City politics.

Explanation:

He was first voted to the New York State Assembly in 1868, and there was a time when he drew three salaries from the public offices of New York City. He was elected to the U.S. State Senate in 1883. In this period, the Tammany machine retained firm influence in the politics of New York, and Plunkitt was voted to a long series of public positions as an incentive for his commitment to the organization.  Plunkitt was the leading name of the 15th Assembly District, a predominantly Irish bastion on the West Side of Manhattan.

the answer is d. party organizers, volunteers, voters and elected officials.