The table below gives the precedence chart for a project.

Activity

Precedes

Time $($weeks$)$

A

$-$

$8$

B

$-$

$3$

C

A

$7$

D

A$,$ B

$3$

E

C

$4$

F

D

$6$Activity C

a$.$ is a critical activity.

b$.$ has some slack time.

c$.$ is a non$-$critical activity.

d$.$ has no slack time.

e$.$ is $"$a$"$ and $"$d$"$ only