The correct answer is option 'D': Oxidation.

Explanation:

Chlorine is a highly reactive element that has a strong oxidizing property. The bleaching action of chlorine is due to its ability to oxidize colored compounds present in the material being bleached. This process involves the transfer of electrons from the colored compounds to chlorine atoms, resulting in the removal of color.

Chlorine acts as an oxidizing agent by accepting electrons from other substances and becoming reduced in the process. In the case of bleaching, chlorine oxidizes the colored compounds by accepting electrons from them, thereby reducing itself.

Chlorine's ability to oxidize is due to its high electronegativity and the presence of an empty 3p orbital in its electron configuration. The electronegativity of an element determines its tendency to attract electrons towards itself in a chemical reaction. Chlorine's high electronegativity allows it to attract electrons from other substances.

The empty 3p orbital in chlorine's electron configuration allows it to accommodate the electrons donated by the colored compounds during the oxidation process. This leads to the formation of chloride ions (Cl-) as chlorine gains electrons.

The oxidation of colored compounds by chlorine results in the breaking of double bonds and conjugated systems, which are responsible for the absorption of visible light and the production of color. The removal of these conjugated systems through oxidation leads to the decolorization or bleaching effect.

In summary, the bleaching action of chlorine is due to its strong oxidizing property. Chlorine acts as an oxidizing agent by accepting electrons from colored compounds, causing them to lose their color. The ability of chlorine to oxidize is a result of its high electronegativity and the presence of an empty 3p orbital in its electron configuration.