Activity C on a CPM network has predecessor B$,$ and has successors D and F$.$ C has duration $7$ days. B$\text{'}$s earliest finish is $20.$ D$\text{'}$s late start is $30,$ while F$\text{'}$s is $27.$ Which of the following is definitely TRUE?

Group of answer choices

D has no slack and is critical..

C is completed before B$.$

F has slack and is not critical.

B has slack and is not critical.

C has no slack and is critical.