An annular disk of mass $M$,inner radius $a$ and outer radius $b$ is placed on a horizontal surface with coefficient of friction $\mu$,as shown in the figure. At some time,an impulse $J_0 \hat{x}$ is applied at a height $h$ above the center of the disk. If $h=h_m$ then the disk rolls without slipping along the $x$-axis. Which of the following statement$(s)$ is(are) correct?
$(A)$ For $\mu \neq 0$ and $a \rightarrow 0, h_m=b / 2$
$(B)$ For $\mu \neq 0$ and $a \rightarrow b, h_m=b$
$(C)$ For $h=h_m$,the initial angular velocity does not depend on the inner radius $a$.
$(D)$ For $\mu=0$ and $h=0$,the wheel always slides without rolling.