Wayne Company had the following inventories at the beginning and end of March: March 1 March 31 $36,000 $30,000 Direct materials Work-in-process Finished goods $18,000 $12,000 $54,000 $72,000 The following additional manufacturing cost data were available for the month of March: Direct materials purchased $84,000 Direct labour payroll $60,000 Direct labour rate per hour $7.50 Factory overhead rate per direct labour hour $10.00 During March, conversion cost added to production was O a. $60,000 O b. $80,000 c. $140,000 O d. $150,000