Two coils are fixed in space at some distance from each other such that there is a flux linkage between them. When coil $1$ has no current and the current in the coil $2$ increases at the rate $15.0$ $\mathrm{A} {\mathrm{s}}^{-1}$, the emf in the coil $1$ is $25.0 \mathrm{mV}$. When coil $2$ has a current of $3.6 \mathrm{A}$, the flux linkage in coil $2$ (in $\mathrm{mWb}$) is 

Hence, the correct answer is 6.