Option (A) is the correct answer.
When separation of two opposite electrical charges is measured then it is known as dipole moment.
More is the electronegativity of an atom more it will have pull of electrons towards itself. For example, in electrons will be pulled towards chlorine atom as it is more electronegative than boron.
Hence, the dipole moment is cancelled out. So, it will have zero dipole moment. In and , fluorine is more electronegative in nature and it is present in both the molecules.
But chlorine is more electronegative that iodine atom. So, the dipole moment of is more than the dipole moment of .
Thus, we can conclude that the correct order of increasing dipole moment is as follows.
Substance 1 has a greater dipole moment, because " Cl " is more electronegative with " I "