The transverse nature of light is shown by

The correct answer is Option (3) → Polarisation of light

Only a transverse wave can be polarised, because polarisation restricts the vibrations to one direction in the plane perpendicular to the direction of travel. A longitudinal wave, whose vibrations are along the direction of travel, cannot show it.

Option (1) Interference of light — Incorrect. Interference shows the wave nature of light; sound waves interfere too.

Option (2) Refraction of light — Incorrect. Refraction is shown by longitudinal waves such as sound as well.

Option (3) Polarisation of light — Correct. Polarisation is possible only for transverse waves.

Option (4) Dispersion of light — Incorrect. Dispersion is the separation of colours and does not depend on the wave being transverse.

NCERT (2026-27):
Introduction – “… Finally in Section 10.7 we will discuss the phenomenon of polarisation which is based on the fact that the light waves are transverse electromagnetic waves.”

Polarisation – “… Light waves are transverse in nature; i.e., the electric field associated with a propagating light wave is always at right angles to the direction of propagation of the wave. This can be easily demonstrated using a simple polaroid.”