Option 1 -> Reflection involves light bouncing off surfaces, but mirages are not caused by simple reflection from a surface.
Option 2 -> Refraction is the bending of light as it passes through layers of air with different temperatures and densities, which is exactly what creates mirages.
Option 3 -> Scattering involves light being deflected by particles in random directions, not the cause of mirages.
Option 4 -> Interference occurs when light waves overlap and combine, which doesn't explain the mirage phenomenon.
Hence, Option 2: Refraction of light -> In deserts, the ground becomes extremely hot, heating the air layer just above it. This creates layers of air at different temperatures and densities. Light from the sky bends (refracts) as it passes through these layers, with hot less-dense air near the ground causing light rays to curve upward. This creates an inverted image of the sky that appears like water on the ground -> correct