Nonesuch Company sells only one product at a regular price of $$7\mathrm{.}50$ per unit. Variable expenses are $60\%$ of sales, and fixed expenses are $$30,000.$ Management has decided to decrease the selling price to $$6\mathrm{.}00$ in hopes of increasing its volume of sales.

What is the contribution margin ratio when the selling price is reduced to $$6\mathrm{.}00$ per unit?

a$.25\%$

b$.75\%$

c$.40\%$

d$.60\%$