As shown in the figure, a disc of mass $\mathrm{m}$ is rolling without slipping with an angular velocity $\omega$. The portion $\mathrm{AB}$ is rough and $\mathrm{BC}$ is smooth. When it crosses point $\mathrm{B}$ disc will be in :

A disc is performing pure rolling on a smooth stationary surface with constant angular velocity as shown in figure. At any instant, for the lower most point of the disc

A smooth inclined plane fixed in a car accelerating on a horizontal road is shown in figure. The angle of incline $\theta$ is related to the acceleration a of the car as $a=g\tan \theta$. If the sphere is set in pure rolling on the incline

A disc of mass $M$ and radius $R$ is rolling with angular speed $\omega$ on a horizontal plane as shown. The magnitude of angular momentum of the disc about the origin $\mathrm{O}$ is