The partial differentiation of excess hydrostatic pressure \overline{u} as a function of r and θ with respect to x is given by _______

• A. \(\frac{∂\overline{u}}{∂x}=\frac{∂\overline{u}}{∂r} cosθ-\frac{1}{r}\frac{∂\overline{u}}{∂θ} sinθ\)
• B. \(\frac{∂\overline{u}}{∂x}=\frac{∂\overline{u}}{∂r} cosθ-\frac{1}{r} \frac{∂\overline{u}}{∂θ} cosθ\)
• C. \(\frac{∂\overline{u}}{∂x}=\frac{∂\overline{u}}{∂r} sinθ-\frac{1}{r} \frac{∂\overline{u}}{∂θ} sinθ\)
• D. \(\frac{∂\overline{u}}{∂x}=\frac{∂\overline{u}}{∂r} sinθ-\frac{1}{r} \frac{∂\overline{u}}{∂θ} cosθ\)