A flat surface of a thin uniform disk $A$ of radius $R$ is glued to a horizontal table. Another thin uniform disk $B$ of mass $M$ and with the same radius $R$ rolls without slipping on the circumference of $A$, as shown in the figure. $A$ flat surface of $B$ also lies on the plane of the table. The center of mass of $B$ has fixed angular speed $\omega$ about the vertical axis passing through the center of A . The angular momentum of B is ${\mathrm{nM} \omega \mathrm{R}^2}$ with respect to the center of A. Which of the following is the value of $n$ ?