Pipeline, Inc incurred $114,600 of actual manufacturing overhead cost last year. The company used a predetermined overhead rate of $6 per direct labor hour. At the end of the reporting period, the company's manufacturing overhead account has a credit balance of $7,200. How many direct labor hours were worked last year?

a. 18,900 hours

b. 20,300 hours

c. 11,900 hours

d. 21,500 hours

e. 43,200 hours

f. 19,100 hours

g. 17,900 hours

h. None of the above.