A Nurse Asks a Patient Diagnosed with Schizophrenia, "What Is

A nurse asks a patient diagnosed with schizophrenia, "What is meant by the old saying 'You can't judge a book by its cover'?" Which response by the patient indicates concrete thinking?

A) "The table of contents tells what a book is about."
B) "You can't judge a book by looking at the cover."
C) "Things are not always as they first appear."
D) "Why are you asking me about books?"