Concept:
Polarization is a phenomenon in which the vibrations of a wave are restricted to a particular direction.
Step 1: Understand wave behavior.}
Only transverse waves can exhibit polarization because their oscillations occur perpendicular to the direction of propagation.
Step 2: Implication for electromagnetic waves.}
When light waves are polarized, it proves that their electric field oscillates in directions perpendicular to the direction of propagation.
Step 3: Conclusion.}
Thus, the phenomenon that confirms the transverse nature of electromagnetic waves is polarization.