A uniform disk of radius \(R\) is mounted on a horizontal axle that exerts a constant frictional torque \(\tau_f\). A block of mass \(m\) suspended from a light string wrapped around the disk is released from rest at time \(t = 0\). At time \(t_1\), the string detaches from the disk, and the disk subsequently slows to rest at time \(t_2\) due to the frictional torque. Which of the following graphs best represents the angular velocity \(\omega\) of the disk as a function of time \(t\) from \(t = 0\) to \(t = t_2\)?