What aspects of the play do not need to be written at all? a character's irony a character's improvisational behavior a character's relationship to others a character's attitude?

I believe the correct answer is second option: character's improvisational behavior.

The improvisation is the act of creating or performing something spontaneously or making something from whatever is available at the certain moment. In the performing arts, act of improvisation is a very spontaneous performance of the actor without specific or scripted preparation, and therefore, it can’t be written in a script.

the answer of "what has three legs but never walks" is a yard stick. this answer can be found at