Artisan Works is owned and operated by a craftsman who makes replicas of historic firearms for museums, sportsmen, and collectors. The data are as follows:

Sales price per unit

$$720$

Variable cost per unit

$$470$

Fixed costs per month

$$6,750$

If Artisan expects to sell $40$ units per month, what is his margin of safety expressed in units per month?

A$.67$ units

B$.11$ units

C$.40$ units

D$.13$ units