What is a "D" Girl? Sopranos Factual Q

Season 2, Episode 7 of “The Sopranos” is titled “The D Girl”. Near the end of the movie, Christopher calls Alicia Witt’s character Amy “a D Girl”, which is obviously an insult, because she replies “I’m a vice-president!”

My question is - what exactly is a “D girl”?

D is for development. A development girl is a girl with a really low position in an entertainment company. She says she’s a VP because he basically called her an intern.

And I thought this was going to have something to do with a singer who’s able to hit a high D.

Oh well, I need to get myself a teevee set.

Cool - thanks!