$P(A^c) = 0.6$; it represents a person who is not a morning person.

$P(A^c) = 0.4$; it represents a person who is definitely an evening person.

$P(A^c) = 0.5$; it represents someone who is both a morning and evening person.

$P(A^c) = 0.6$; it represents the sample space of all people.