Which one of the following statement best reflects the position of proponents of the variable costing method?

A variable manufacturing overhead costs do not vary with production and thus should be considered a product cost.

B variable manufacturing overhead costs do vary with production and thus should be considered a period cost.

C fixed manufacturing overhead costs do not vary with production and thus should be considered a product cost.

D fixed manufacturing overhead costs do vary with production and thus should be considered a product cost.?