According to Rosenhan's Being Sane in Insane Places, how gains can be made in distinguishing the ...

According to Rosenhan's Being Sane in Insane Places, how gains can be made in
  distinguishing the sane from the insane?
 
  a. Admitting insane people to psychiatric hospitals and then determining if and how they
  are discovered to be insane.
  b. Admitting sane people to psychiatric hospitals and then determining if and how they are
  discovered to be insane.
  c. Admitting sane people to psychiatric hospitals and then determining if and how they are
  discovered to be sane.
  d. Admitting insane people to psychiatric hospitals and determining if and how they are
  discovered to be sane.