The Democratic Socialists of America is not a communist party. Answer no.
You can always disclose membership in the Democratic Socialists of America elsewhere to forestall any suspicion of deception.
The term communist party is defined thus in 8 CFR 313.1:
Communist Party includes:
(1) The Communist Party of the United States;
(2) The Communist Political Association;
(3) The Communist Party of any state of the United States, of any foreign state, or of any political or geographical subdivision of any foreign state;
(4) Any section, subsidiary, branch, affiliate, or subdivision of any such association or party;
(5) The direct predecessors or successors of any such association or party, regardless of what name such group or organization may have used, may now bear, or may hereafter adopt; and
(6) Any communist-action or communist-front organization that is registered or required to be registered under section 786 of title 50 of the United States Code, provided that the applicant knew or had reason to believe, while he or she was a member, that such organization was a communist-front organization.