Final answer:
The quote from Boss Tweed that is ironic in light of the scene illustrated in Nast's cartoon is (c) Vote early and often.
Step-by-step explanation:
The quote from Boss Tweed that is ironic in light of the scene illustrated in Nast's cartoon is (c) Vote early and often. In Nast's cartoon, the control of Boss Tweed over the election process in New York is depicted, showing the corruption involved in machine politics. Boss Tweed's quote about voting early and often is ironic because it implies that he encourages and benefits from voter fraud and manipulation, further highlighting the corrupt nature of his political activities.