$($CPA$)$ Diva Co$.$ wants to establish a selling price that will yield a gross margin of $40\%$ on the sales revenue of a product whose cost is $$12\mathrm{.}00$ per unit. The selling price should be:

a$.$ $$16\mathrm{.}80.$

b$.$ $$19\mathrm{.}20.$

c$.$ $$20\mathrm{.}00.$

d$.$ $$30\mathrm{.}00.$