Mirage is a phenomenon due to

The correct answer is Option (3) → total internal reflection

Option (1) refraction — Incorrect. Refraction only changes the direction of a ray that passes into the other medium. A mirage is an example of total internal reflection, in which no light passes into the other medium and the ray is sent back.

Option (2) reflection — Incorrect. When a surface reflects light, some part of it is normally transmitted. So the reflected ray is always less intense than the incident ray. A mirage is the total reflection of light, with no transmission.

Option (3) total internal reflection — Correct. When light goes from a denser to a rarer medium at an angle of incidence greater than the critical angle, refraction is not possible. The light is then totally reflected back. A mirage is an example of this phenomenon.

Option (4) scattering — Incorrect. Scattering sends light off in many directions from small particles in its path. It does not totally reflect a ray at the boundary of two media.

NCERT (2026-27):
Summary – “2. The critical angle of incidence i_c for a ray incident from a denser to rarer medium, is that angle for which the angle of refraction is 90°. For i > i_c, total internal reflection occurs. Multiple internal reflections in diamond …, totally reflecting prisms and mirage, are some examples of total internal reflection.”