Assume that Product Z is made of two units of A and four units of B$.$ A is made of three units of C and four of D$.$ D is made of two units of E$.$

Lead times for purchase or fabrication of each unit to final assembly are: Z take two weeks; A$,$ B$,$ C$,$ and D take one week each; and E takes three weeks.

Fifty units are required in Period $10.($Assume that there is currently no inventory on hand and no scheduled receipts of any of the these items$)$

$($a$)$ Show the bill of materials $($product structure tree$).$