(Chapter 4, \#5, p.138) Classify each of the following as an example of a mandatory, discretionary or originator-controlled policy, or a combination thereof. Justify your answers. (a) The file access control mechanisms of the UNIX family of operating systems. (b) A system in which no memorandum can be distributed without the creator's consent. (c) A military facility in which only generals can enter a particular room. (d) A university registrar's office, in which a faculty member can see the grades of a particular student, provided that the student has given written permission for the faculty member to see them