If direct materials for one unit of product are $9.00, direct labor for one hour is $15.00, manufacturing overhead costs are $5.00 per direct labor hour, and one-fourth hour of direct labor is required to produce one unit of product, how much are the labor and overhead costs for one unit of product?
a. $5.00.
b. $2.50.
c. $20.00.
d. $15.00.