The common stock of Mountain Farms has yielded 14.2 percent, 11.7 percent, 3.4 percent, -2.8 percent, and 15.8 percent over the past five years, respectively. What is the geometric average return? Select one: a. 7.91 percent b. 8.03 percent c. 8.22 percent d. 8.27 percent e. 7.64 percent