If Troy purchases the S1798 units from Duncan, the capacity Troy used to manufacture these parts would be idle. Should Troy decide to purchase the parts from Duncan, the unit cost of S1798 would

a. decrease by $3,700.

b. decrease by $5,600.

c. increase by $3,600.

d. increase by $5,300.

Please show your work, thank you

Troy Instruments uses ten units of Part Number S1798 each month in the production of scientific equipment. The unit cost to manufacturing one unit of S1798 is presented below $ 4,000 Direct materials 400 Materials handling (10% of direct materials cost) Direct manufacturing labor Indirect manufacturing (200% of direct labor) 6,000 12,000 $22.400 Total manufacturing cost Materials handling represents the direct variable costs of the Receiving Department that are applied to direct materials and purchased components on the basis of their cost. This is a separate charge in addition to indirect manufacturing cost. Troy's annual indirect manufacturing cost budget is one-fourth variable and three-fourths fixed. Duncan Supply one of Troy's reliable vendors, has offered to supply Part Number S1798 at a unit price of $17,000