A project consists of seven activities. The following table shows the estimated time of the activities and the precedence relations.

Activity

Estimated durations $($days$)$

Immediate predecessor

A

$9$

B

$10$

C

$5$

A

D

$3$

A

E

$6$

B$,$ C

F

$3$

B$,$ C

G

$4$

D$,$ E

Select all critical activities