Task: Class Definition Understanding (ontology: Human_Society/EmotionOntology)

Which of the following definitions best describes 'smiling'?

A. A facial expression behaviour in which the eyes are closed.
B. Characteristic facial expressions that are made when a person is undergoing a so-called "basic" emotions. These are canonical, that is, individual facial expressions when undergoing emotions can vary or not change at all. However, research indicates evidence for the existence of characteristic canonical facial expressions that are displayed when experiencing certain emotions even across cultures.
C. A facial expression behaviour in which the person smiles.
D. A facial expression behaviour which appears very neutral (showing no expression).

Answer: A facial expression behaviour in which the person smiles.