Illusion of choice
Also said as Fake choice, Choice without consequence
The player picks between options that all lead to the same thing, with the difference limited to a line or two. It feels like a decision until someone replays it.
Used well it is cheap and gives a scene some personality, since a player choosing a tone is doing something real. Discovered, it can sour every other choice in the game.
Say it
“These three replies are an illusion of choice, and that is fine: let each one set the tone of the next line, but do not promise on screen that anyone will remember it.”
Where you’ve seen it
The Walking Dead by Telltale puts "will remember that" on screen after your choices. It makes each one feel recorded, while most of the plot goes on the same way.
Not to be confused with agency
Agency changes what happens next. An illusion of choice changes how the same thing felt while it happened.