Suppose that you estimated a production function for various professional tennis players. The measure of output is the percentage of matches played by a player that are won by the player. Inputs include the average number of hours per week spent practicing tennis. Suppose that your results indicate that the marginal product associated with practice time is 0.07 for Anna Kournikova, 0.09 for Venus Williams, and 0.16 for Maria Sharapova. If the law of diminishing marginal returns holds, which of the three players has spent the most time practicing?