The administrators of the local hospital are interested in identifying the various costs and expenses that are incurred in producing a patient's X$-$ray. A list of such costs and expenses is presented below:

The administrators want these costs and expenses classified as $($a$)$ direct materials, $($b$)$ direct labour, or $($c$)$ service overhead.

Salaries for the X $-$ray machine technicians

Wages for the hospital janitorial personnel

Film costs for the $x-$ray machines

Property taxes on the hospital building

The salary of the $x-$ray technicians' supervisor

Electricity costs for the $x-$ray department

Maintenance and repairs on the $x-$ray machines

X$-$ray department supplies