How does Williams's choice to include the scene with the unicorn contribute to the meaning of the play?

It hints that Jim realizes that the invitation was a trap to set him up with Laura, giving the play a deceitful note.

It suggests that Jim's interaction with Laura takes him back to his childhood, giving the play a sentimental note.

It confirms that Laura lives in a fantasy world, giving the play a fragile note.

It indicates that Jim is playing along with Laura so as not to hurt her feelings, giving the play a compassionate note.