The following table lists the components needed to assemble an end item. Assume there is no on $-$ hand inventories.

Item Direct Components

End item A $(1),$ ?B $(5),$ ?C $(1)$

A E $(4),$ ?F $(2)$

B D $(3),$ ?E $(2)$

C F $(4)$

D

E

F E $(3)$

If $6$ ?units of the end item are to be assembled, how many units of component E are needed?