A disc of radius R rotates at an angular velocity Ω inside a disc shaped container filled with oil of viscosity μ, as shown in figure. Assuming a linear velocity profile and neglecting shear stress on the outer disc edges, the formula for viscous torque on the disc is

• A. \(\frac{{\pi \mu {\rm{\Omega }}{R^2}}}{h}\)
• B. πμΩhR3
• C. \(\frac{{\pi \mu {\rm{\Omega }}{R^5}}}{h^2}\)
• D. \(\frac{{\pi \mu {\rm{\Omega }}{R^4}}}{h}\)