• Iodine molecules are a form of non-polar constituent particles which form crystals and held together by London force (or induced dipole-dipole interaction) which is a weakly dispersion force. It is possible when 2 adjacent atoms of molecules come in a position where a temporary dipole is formed, it is the weakest intermolecular force.

Other 3 options (ii) dipole-dipole interactions (iii) covalent bonds and (iv) coulombic forces are not the case of iodine molecules because they require polarity or ionic entities to occur.