A simple CPM network has throe activities, D$,$ E$,$ and F$.$ D is an immediale predecessor of E and:

of $F,E$ is an immediate predecessor of $F.$ The activily duralions are $D=4,E=3,F=8.$

Select one:

A$.$ Slack of $D$ is $3$ periods.

B$.$ The critical pathis D$-$EF diration $15.$

C$.$ Slock at $E$ is $3$ periods.

D$.$ The erticai poth is D$-5,$ duration $12.$