The following activities occur at Greenwich Corporation, a company that manufactures a variety of products.

a$.$ Receive raw materials from suppliers.

b$.$ Manage parts inventories.

c$.$ Do rough milling work on products.

d$.$ Interview and process new employees in the personnel department.

e$.$ Design new products.

f$.$ Perform periodic preventive maintenance on general$-$use equipment.

g$.$ Use the general factory building.

h$.$ Issue purchase orders for a job.

Required:

Classify each of the activities above as either a unit$-$level, batch$-$level, product$-$level, or organization$-$sustaining activity.