You have the following data: D$1=$ $$1\mathrm{.}80$; P$0=$ $$36\mathrm{.}00$; and g $=3\mathrm{.}00\%($constant$).$ What is the cost of equity from retained earnings based on dividend growth approach?

a$.$

$8\mathrm{.}00\%$

b$.$

$8\mathrm{.}50\%$

c$.$

$5\mathrm{.}00\%$

d$.$

$7\mathrm{.}70\%$