You observe the investment performance of 500 portfolio managers and rank them by investment returns during the year. 25% of all managers are truly skilled and therefore always fall in the top half, but the others fall in the top half purely because of good luck. Which fraction of this year's top-half managers would you expect to be top-half performers next year? a. 65.67% b. 66.67% C.64.67% d. 63.67%