A $$450-$per$-$month apartment requires eight prospects before it

is leased during active market conditions. If a $$35$ classified ad

must be run for five days to attract this number of prospective

tenants, the prospect$-$per$-$ad cost figure for this marketing effort

would be

$$56\mathrm{.}25$

$$4\mathrm{.}38$

$$21\mathrm{.}87$

$$14\mathrm{.}12$