A client being admitted to the inpatient unit suddenly removes a knife from his coat pocket and ...

A client being admitted to the inpatient unit suddenly removes a knife from his coat pocket and
  threatens to kill himself or anyone who tries to take him into a room.
 
  A psychiatric emergency code
  is called and the client is safely disarmed and placed in seclusion. The rationale for use of seclusion
  was that the client
  a. clearly evidenced a thought disorder, rendering him incapable of rational
  decision.
  b. presented a clear and present danger to self and others.
  c. presented a clear escape risk.
  d. was psychotic.