Explanation:

- Bleaching action of Chlorine:

- Chlorine acts as a bleach by participating in a chemical reaction.

- Option 1: Oxidation

- Chlorine's bleaching effect is largely due to its ability to oxidize colored substances.

- Chlorine releases oxygen in water which removes color by breaking chromophores.

- Option 2: Hydrolysis

- Hydrolysis involves the chemical breakdown of a substance with water.

- Chlorine undergoes hydrolysis in water, but the bleaching action specifically stems from oxidation.

- Option 3: Redox

- A redox reaction involves both reduction and oxidation processes.

- While chlorine can participate in redox reactions, its bleaching action is primarily due to oxidation.

- Option 4: Decomposition

- Decomposition involves breaking down compounds into simpler products.

- Chlorine bleaching does not primarily involve decomposition.

- Correct Answer: Oxidation