Dagmar Is a Musician and She Loves the Fact That

Dagmar is a musician and she loves the fact that she constantly hears new melodies in her head. In fact, she cannot remember a time when she did not hear music. Why is this NOT an example of an obsession?

A) Obsessions must be accompanied by ritualistic actions.
B) Obsessions must come on suddenly in response to a stressful life event.
C) Obsessions must be voluntary thoughts that a person knows are irrational.
D) Obsessions must be intrusive thoughts the person finds disturbing.