Which of the CAPITALIZED words provides the least negative interpretation of Sam's behavior?

Sam seemed a bit COLD at the party; he hardly spoke to anyone and seemed unhappy.

Sam seemed a bit INDIFFERENT at the party; he hardly spoke to anyone and seemed unhappy.

Sam seemed a bit ANTISOCIAL at the party; he hardly spoke to anyone and seemed unhappy.

Sam seemed a bit WITHDRAWN at the party; he hardly spoke to anyone and seemed unhappy.