Final answer:
The theory of expressing basic human emotions suggests that artists aim to convey specific emotions, such as tragedy, ecstasy, or doom, through their artwork.
Step-by-step explanation:
The theory that all works portray a single emotion is known as the "theory of expressing basic human emotions."
This theory suggests that artists aim to convey specific emotions, such as tragedy, ecstasy, or doom, through their artwork. Artists believe that when viewers have an emotional response to their work, it indicates successful communication of those basic human emotions.