Activity D on a CPM network has predecessors B and C, and has successor F. D has durationB's earliest finish is 18, while C's isF's late start isWhich of the following is true? a. B is a critical activity. b. C is completed before B. c. D has no slack but is not critical. d. D is critical, and has zero slack. e. All of the above are true.

A simple CPM network has three activities, D, E, and F. D is an immediate predecessor of E and of F. E is an immediate predecessor of F. The activity durations are D=4, E=3, F=8.a. The critical path is D-E-F, durationb. The critical path is D-F, durationc. Slack at D is 3 units d. Slack at E is 3 units e. Both a and c are true

A simple CPM network has three activities, A, B, and C. A is an immediate predecessor of B and of C. B is an immediate predecessor of C. The activity durations are A=4, B=3, C=8.a. The critical path is A-B-C, durationb. The critical path is A-C, durationc. The critical path is A-B-C, duration 13.5 d. The critical path cannot be determined without knowing PERT expected activity times. e. The network has no critical path.