Question $7(1$ point$)$

Activity D on a CPM network has predecessors $B$ and $C,$ and has successor $F.$ D has duration $6.$ B$\text{'}$s earliest finish is $18,$ while C$\text{'}$s is $20.$ F$\text{'}$s late start is $26.$ Which of the following is definitely true?

B is a critical activity.

C is completed before B$.$

$F$ is critical and has zero slack.

D has no slack but is not critical.

$D$ is critical and has zero slack.