单选题 An analyst collects the following set of ten returns of a firm from the past: 2.2 percent, 6.2 percent, 8.9 percent, 9.3 percent, 10.5 percent, 11.7 percent, 12.3 percent, 14.1 percent, 15.3 percent, and 18.4 percent. What value is closest to the geometric mean return of this firm?