What Is the Difference Between a Tag Definition and a Tagged

What is the difference between a tag definition and a tagged value?

A) The properties of metaclasses are sometimes referred to as tag definitions. When a metaclass is applied to a model element, the values of the properties may be referred to as tagged values.
B) The properties of stereotypes are sometimes referred to as tagged values. When a stereotype is applied to a model element, the values of the properties may be referred to as tag definitions.
C) The properties of stereotypes are sometimes referred to as tag definitions. When a stereotype is applied to a model element, the values of the properties may be referred to as tagged values.
D) They are synonyms.