(a) The requirement is to identify the password that
would be most difficult to crack. A password is a secret series of
characters that enables a user to access a file, computer, or program;
ideally, the password should be something nobody could
guess. Answer (a) is correct because OrCA!FlSi does not seem
like a password that one would guess or even recall if seen briefly.
Answers (b), (c), and (d) are all incorrect because they represent
passwords that would be easier to identify.