Which of the following statements are correct?

I) Dipole-dipole interaction energy between stationary polar molecules (as in solids) is proportional to  $\frac{1}{r^3}$

II) Besides dipole-dipole interaction, polar molecules can interact by London forces also

III) London forces are important only at short distances $(~500pm)$  and their magnitude depends on the polarisability of the particle.

IV) Induced dipole moment depends upon the dipole moment present in the permanent dipole and the polarisability of the electrically neutral molecule.