The following data apply to Stratford Lid Direct materials inventory, beginning of the year 5 500 Direct materials inventory, end of the year 3 000 Direct materials purchased during the year 45 000 Work in process inventory, beginning of the year 9 000 Manufacturing overhead applied during the year 20 000 Work in process inventory, end of the year 14 000 Predetermined overhead rate-200 per cent of direct labour cost Calculate the amount of direct labour cost incurred during the year. O a. $18 000 O b. $20 000 O c. None of the given answers X O d. $10 000