Final answer:
New York Magazine, founded in 1968, was the first city magazine aimed at a national audience, setting a standard for the city magazine genre.
Step-by-step explanation:
The first city magazine aimed at a national audience was B. New York Magazine. Founded in 1968 by Milton Glaser and Clay Felker, New York Magazine began as a supplement to the New York Herald Tribune newspaper before becoming an independent publication. It was, and still is, known for its in-depth coverage of New York City's culture, lifestyle, politics and more. Its success set a precedent for the city magazine genre, with many other cities following suit by launching their own local publications aiming to capture the essence of their city for both residents and a wider national audience.