Physics · Wave Motion and Sound

A thin oil film on a water surface appears colored because of thin-film interference which involves the interference of light waves reflecting off the top surface of a film with the waves reflecting from the bottom surface. Hence, Option B is correct.

Diffraction is a phenomenon that occurs when waves, such as light or sound waves, encounter an obstacle or a slit and bend around it. However, diffraction is not the primary reason for the colors seen in an oil film on the water surface. 

A thin oil film on a water surface appears coloured because of thin- film interference which involves the interference of light waves reflecting off the top surface of a film with the waves reflecting from the bottom surface. Hence, Option B is correct.

Dispersion is the phenomenon where different colors of light bend at different angles when passing through a medium, such as a prism. While dispersion can produce colors, it is not the primary reason for the colors seen in an oil film on water. 

Polarization refers to the orientation of light waves in a specific direction. It can produce specific effects, but it is not the primary reason for the colors seen in an oil film on water.