Question

Kayley just feels happy today. she can't remember exactly when the feeling started, and she can't think of a particular reason she should feel this way. kayley is experiencing a(n):

Answer 1

Kayley is experiencing a mood.
Mood is a term we use to denote the way we are feeling during a particular time. In the case above, Kayley is happy without any particular cause which brought about that feeling - she has been feeling good and energetic the entire day, so we can say that her mood for the day has been a happy one.