Right option is (d) Corona Treatment
The best explanation: Corona treatment involves the application of a high voltage (10–40 kV) low frequency (10–20 kHz) discharge across a fixed air gap between an electrode and an earthed conductive roller which carries the film. The corona treatment cleans, oxidizes and activates the surface by converting it from a nonpolar to a polar state by bombarding it with ozone, O2 and free radicals of O2. This increases the surface energy and results in the substrate surface being more compatible with a freshly oxidized thermoplastic surface, thus promoting adhesion between the two.