Given the following information for an AOA network:

$\backslash$table$[[,,$Immediate$],[$Activity$,$Duration $($days$),$Predecessor$($s$)],[$A$,4,$none$],[$B$,2,$A$],[$C$,7,$none$],[$D$,4,$A$],[$E$,5,$B$,$C$,$D$]]$

How many critical activities are there in this AOA network?

Keep your own AOA graph.

Select one:

a$.$ five critical activities

b$.$ two critical activities

c$.$ three critical activities

d$.$ four critical activities