Question: Oszkár Kálmán was the first lead of a one act opera by which composer?
Sentence (from "Bluebeard's Castle"): The opera lasts only a little over an hour and there are only two singing characters onstage: Bluebeard ("Kékszakállú "), and his new wife Judith ("Judit " ); the two have just eloped and Judith is coming home to Bluebeard's castle for the first time.
Relevant evidence: No