The momentum equation is \( \rho\frac{Du}{Dt}=-\frac{\partial p}{\partial x}+\frac{\partial \tau_{xx}}{\partial x}+\frac{\partial \tau_{yx}}{\partial y}+\frac{\partial \tau_{zx}}{\partial z}+\rho f_x\). Which of these statements about sign convention can be inferred from this equation?

• A. Pressure force is taken as negative
• B. Tensile force is taken as negative
• C. Pressure force is taken as positive
• D. Pressure force is unsigned