The short story Girls by Oksana Zabuzhko (in Your Ad Could Go Here) features Darka meeting a girl of apparently high social status:
Rivka... smelled of homemade vanilla cookies, vacations at a spa in the Caucasus, third-generation antiques confiscated during the Bolshevik revolution, and a five-room apartment of the sort reserved for only the most privileged of Soviet families, in a building erected by prisoners of war for the elite. Such a start in life does little to encourage an instinct for self-preservation, so it was Darka, who Rivka carelessly attempted to treat with all her studied arrogance towards those who had never darkened the threshold of such a five-room apartment in a building erected by prisoners of war, who taught Rivka her first lesson in survival in a society sufficiently transformed so that neither her grandfather the prosecuting attorney nor her father the chief manager were able to secure for her what was the most valuable: a more bankable nationality to declare in that fifth blank on her passport.
What, exactly, was the "fifth blank on her passport"? And what was a "more bankable nationality"?
The book later mentions that Darka later felt very guilty for her interactions with this girl:
We can count among the long-term consequences of events the mixed feelings of guilt and shame that from then on dogged Darka in her every encounter with a Jewish person...
Is the book implying that Rivka was Jewish, and that that's why she was out of political favor (in spite of the fact that her grandfather was evidently "an agent of the cheka, the brutal secret police")?