a. Tubing used in manufacturing bicycles.
b. Wages paid by an automobile manufacturer to employees who test-drive completed automobiles.
c. Property taxes on machinery.
d. Gold bullion used by a jewelry manufacturer.
e. Wages of assembly-line workers who package frozen food.
f. Salary of plant superintendent.
g. Electricity used in factory operations.
h. Salary of a nurse in a factory first-aid station.