Solve and show work for #10, please and thank you! Teacher said it was A but I think it is D?

9. The following rate of returns for Stock A [Use this data to answer questions 9 and 10] Year Stock A 200X 200Y 40% 15% -10% Calculate the average return of Stock A 10% b) 15% c.18% d.22% e, none of the given ones a. 10. The standard deviation of returns of Stock A is: @ 25% 14.7% c. 12% d. 9.3% d.none of the given ones b