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 $A=4,B=3,C=5.$

A$.$ The critical path is A$-$C$,$ duration $10\mathrm{.}5$

B$.$ The network has no critical path.

C$.$ The critical path is $A-B-C,$ duration $12.$

D$.$ The critical path is A$-$B$-$C$,$ duration $9.$

E$.$ The critical path cannot be determined without knowing PERT expected activity times.