The correct response is: In a soliloquy, the speaker assumes they cannot be heard.
A soliloquy is a speech in which a character speaks their thoughts aloud, typically while alone on stage, and is generally meant to convey their inner thoughts to the audience without any intention of being overheard by other characters. In contrast, a monologue is more of an extended speech by a character that can be directed towards other characters or the audience, often for the purpose of advancing the plot or expressing feelings.