Consider the following project:

Activity Time Predecessor

A

$1$

$2$

$-$

B

$1$

$0$

$-$

C

$9$

$$A

D

$1$

$5$

$$A

E

$7$

$$B

F

$8$

$$D

$,$

$$E

G

$1$

$3$

$$C

$,$

$$F

Which activity has a slack time that is different from all others