Indicate whether each of the following is a product cost or a period cost:

$\_\_\_\_\_\_\_\_\_\_$a$.$ Electricity for lighting a factory building.

$\_\_\_\_\_\_\_\_\_\_$b$.$ Costs of delivering finished bicycles to dealers.

$\_\_\_\_\_\_\_\_\_\_$c$.$ Cost of a store detective in a retail establishment.

$\_\_\_\_\_\_\_\_\_\_$d$.$ Cost of eggs in a bakery.

$\_\_\_\_\_\_\_\_\_\_$e$.$ Cost of chocolate to a candy manufacturer.

$\_\_\_\_\_\_\_\_\_\_$f$.$ Salary of injection molding machine operator in a plastics factory.

$\_\_\_\_\_\_\_\_\_\_$g$.$ Salary of a sewing machine operator in a clothing factory.

$\_\_\_\_\_\_\_\_\_\_$h$.$ Depreciation of a freezer in an ice cream plant.