Panamint Systems Corporation is estimating activity costs associated with producing disk drives, tapes drives, and wire drives. The indirect labor can be traced to four separate activity pools. The budgeted activity cost and activity base data by product are provided below.

$\backslash$table$[[,$Activity Cost,Activity Base,,$],[$Procurement$,$$$366,900,$Number of purchase orders,,$],[$Scheduling$,,239,000,$Number of production orders,,$],[$Materials handling,$482,000,$Number of moves,,$],[$Product devel,ment,$784,400,$Number of engineering changes,,$],[$Production$,1,588,200,$Machine hours,,$],[\backslash$table$[[$Number of$],[$Purchase$],[$Orders$]],\backslash$table$[[$Number of$],[$Production$],[$Orders$]],\backslash$table$[[$Number$],[$of$],[$Moves$]],\backslash$table$[[$Number of$],[$Engineering$],[$Changes$]],\backslash$table$[[$Machine$],[$Hours$]],\backslash$table$[[$Number$],[$of$],[$Units$]]],[$Disk drives,$3,840,290,1,310,15,2,000,2,500],[$Tape drives,$2,400,205,560,5,9,600,3,900],[$Wire drives,$12,900,840,3,700,25,11,300,2,600]]$

The activity$-$based cost for each disk drive unit is

$$ a$.$ $$745\mathrm{.}12$

b$.$ $$226\mathrm{.}69$

c$.$ $$255\mathrm{.}63$

d$.$ $$19\mathrm{.}17$