The following data relate to two output levels of a department: Machine hours Overheads 18,000 380,000 20,000 390,000 The variable overhead rate was 5 per hour. The amount of fixed overhead was A 230,000 B 240,000 C 250,000 D 290,000 Fixed costs are conventionally deemed to be: A Constant per unit of output B Constant in total when production volume changes C Outside the control of management D Those unaffected by inflation