Hotel Donatello budgeted room attendance to clean $600$ rooms in $300$ hours and budgeted wages at $$1,200.$ For the period, the room attendants cleaned $660$ rooms in $320$ hours and were paid $$1,344.$ Thus, the volume variance is$.$

a$.$ $$120($F$).$

b$.$ $$120(U).$

c$.$ $$80(F).$

d$.$ $$80(U).$