$4.$ Which one of the following is not a direct material?

a$.$ A tire used for a lawn mower

b$.$ Plastic used in the covered case for a home PC

c$.$ Steel used in the manufacturing of steel$-$radial tires

d$.$ Lubricant for a ball$-$bearing joint for a large crane

$5.$ Direct materials and direct labor of a company total $$8,000,000.$ If manufacturing overhead is

$$4,000,000,$ what is direct labor cost?

a$.$ $$4,000,000$

b$.$ $$8,000,000$

c$.$ $$0$

d$.$ Cannot be determined from the information provided

$6.$ As inventoriable costs expire, they become

a$.$ selling expenses.

b$.$ gross profit.

c$.$ cost of goods sold.

d$.$ sales revenue.