Lines of Communication - S4-E11
Trivia: Marcus tells the Mars resistance fighters that he was raised on the planet Arisia. J. Michael Straczynski used that name as an homage to one of his favorite science fiction book series, E.E. "Doc" Smith's Lensmen novels, in which the Arisians were the good guys. (00:16:00)
Chosen answer: It was a piece composed expressly for the episode by Christopher Franke, who simply called it "Bar Background Music."
Jean G