Given is a CPM project network diagram as shown below.

$$

Activity

Start

A

B

C

D

E

F

G

H

End

day

$0$

$5$

$6$

$9$

$6$

$9$

$8$

$5$

$4$

$0$

a$)$ The Project Completion time $=?$ days.

$$

b$)$ The Earliest Start time, ES$,$ of Activity G $=?$days.

$$

c$)$ The Latest Finish time, LF$,$ of Activity C $=?$ days..

$$

d$)$ The critical activities are $=?($ex$.$ Fill in the answer as: ABCD$)$