Been to NY a few times (admittedly not the Bronx) and never heard them refer to their railway as "the el". Been to Chicago a few times too and they refer to their railway as the el all the time. Maybe they do in New York but, even if so, the clue would have been better if it had used Chicago as, at best, the NY railway is the "third avenue el" or "bronx el" whereas Chicago's is the el.