In an underground mining operation, a vertical shaft is being sunk through a rock formation. The depth of the shaft is 400 meters. The density of the rock is 2,700 kg/m, and the acceleration due to gravity (g) is 9.81 m/s. Calculate the total vertical stress (v) at the base of the shaft, taking into account both the weight of the overlying rock and the gravitational stress. Round your answer to the nearest tenth of a MPa. Answer A. 21.2 MPa B. 10.7 MPa C. 19.7 MPa D. 14.9 MPa