To mop-clean a floor, a cleaning machine presses a circular mop of radius R vertically down with a total force F and rotates it with a constant angular speed about its axis. If the force F is distributed uniformly over the mop and if coefficient of friction between the mop and the floor is μ, the torque applied by the machine on the mop is

• A. \(\frac{2}{3}\mu FR\)
• B. \(\frac{{\mu FR}}{6}\)
• C. \(\frac{{\mu FR}}{3}\)
• D. \(\frac{{\mu FR}}{2}\)