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$=8.$

Select one:

a$.$ both the critical path is D$-$F$,$ duration $12$ and slack at D is $3$ periods.

b$.$ the critical path is D$-$E$-$F$,$ duration $15.$

c$.$ The critical path is D$-$F$,$ duration $12.$

d$.$ Slack at D in $3$ periods.

e$.$ Slack at E is $3$ periods.