The production function for laser eye surgery is given by $Q = 20K^{0.5}L^{0.5}$, where $Q$ is the number of laser eye surgeries performed per day, $K$ is the number of eye surgery machines (which is fixed at 2 in the short run), and $L$ is the number of employees. The marginal product of labor for $L = 3$ is
28.28
11.71
9.43
8.99