What does inefficient use of labour imply? favourable variable overhead efficiency variance. O favourable variable overhead spending variance. unfavourable variable overhead efficiency variance. unfavourable variable overhead spending variance. Which of the following may cause an unfavourable variable overhead spending variance? the use of excessive quantities of variable overhead items. the payment of lower prices for variable overhead items used. the use of excessive quantities of the variable overhead allocation base. the payment of higher prices for variable overhead items used