What is a major characteristic of roman noir ?
-identity of criminal
-one narrative is featured
-sexuality and eroticism play a major role
-one major crime is committed

Sexuality and eroticism play a major role.

Explanation:

Noir fiction (or roman noir) is a dark form of literature. It is written to show the darkness and evilness of the side of society we don't see. The other three options can relate to basically any form of literature, whereas only one (3) is typically only ever seen in Roman Noir. While the story is focused on either the victim or perpetrator, that doesn't necessarily mean that the identity of the criminal is always known. Separative narratives and multiple crimes can also take place in Noir fiction. The only real unique characteristic would be the story's portrayal of sex and eroticism.

I feel like that was poorly explained but I hope this helps anyway.

the time most likely will repeat, in the story.