Use this scenario for the next six questions.

A project consists of the following activities:

$\backslash$table$[[$Activity$,$Activity Predecessor,Time $($weeks$)],[$A$,--,8],[$B$,--,12],[$C$,$A$,$B$,4],[$D$,$A$,$B$,10],[$E$,$C$,7],[$F$,$D$,9],[$G$,$E$,$F$,8]]$

Using the information in the table, the earliest finish $($EF$)$ time for activity $D$ is

a$.20$ weeks

b$.22$ weeks

c$.15$ weeks

d$.11$ weeks

What is the Anount of slack associated with f