Polka King Gifts had the following costs in March when $400$ ceramic statues were produced: materials, $$4,200$; labor cost, $$1,600$; depreciation, $$800$; rent, $$700$; and other fixed costs, $$500.$ If production changes to $500$ units and production still remains within the relevant range, which of the following costs will stay the same?

A$.$ Total variable cost

B$.$ Variable cost per unit

C$.$ Fixed cost per unit

D$.$ None of these answer choices is correct.

E$.$ Total cost per unit