Answer:
d. character making a quick comment to the audience that other characters do not hear
Step-by-step explanation:
a remark or passage in a play that is intended to be heard by the audience but unheard by the other characters in the play.
An aside is a dramatic device in which a character speaks to the audience. By convention the audience is to realize that the character's speech is unheard by the other characters on stage. It may be addressed to the audience expressly or represent an unspoken thought.