Destiny Corporation has experienced returns of $9\%,18\%,27\%$ and $-15\%$ returns over the past four years. Given this information, calculate the company's geometric average returns.

A$)6\mathrm{.}75\%$

B$)8\mathrm{.}55\%$

C$)10\mathrm{.}35\%$

D$)12\mathrm{.}15\%$

E$)14\mathrm{.}05\%$