# The value of a certain physical quantity is $X \large\frac{\mu\: g \times cm^3 }{(millisecond)^2}$ Its value in $\large\frac{mg \times mm^3}{\mu s^2}$ is

$\begin {array} {1 1} (A)\;10^{-3}X & \quad (B)\;10^{-6}X \\ (C)\;10^{-9}X & \quad (D)\;\text{none of these} \end {array}$

$10^{-6}$X