B. In Unix, name three ways in which the access rights of a file may be modified (hint: some may require root access).
C. In one sentence, define thrashing in terms of working sets.
D. True or false: LRU page replacement does not exhibit Belady's anomaly.
E. True or false: public key encryption is based on the assumption that given two extremely large numbers, discovering their greatest common denominator is a very hard problem.