In the Context of Mental Illness, "Revolving Door" Refers to a Consequence

In the context of mental illness, "revolving door" refers to a consequence of

A) institutionalization, wherein people remain incarcerated in the institutions for long periods of time.
B) homelessness, wherein people do not get help for their ongoing mental problems.
C) deinstitutionalization, wherein people leave institutions only for brief periods of time before needing help again.
D) homelessness, wherein people with severe mental illness are victims of crimes.