7. 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, duration 15. B) The critical path is A-C, duration 12. C) 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.