An investor purchases a $30-$year, zero$-$coupon bond with a face value of $$5,000$ and a yield to maturity of $6\mathrm{.}5\%.$ He sells this bond ten years later. What is the rate of return on his investment, assuming yield to maturity does not change?

A$.6\mathrm{.}5\%$

B$.5\mathrm{.}2\%$

C$.3\mathrm{.}9\%$

D$.3\mathrm{.}25\%$