Answer:
Cl₂ > Br₂ > I₂
Step-by-step explanation:
An oxidizing agent gains electron for itself by removing electrons from other reactants during a reaction. Oxidation is the loss of electrons. Chlorine can take electron from bromine and chlorine while bromine can take electron from iodine, therefore chlorine is a more oxidizing agent than bromine and iodine while bromine is a more oxidizing agent than iodine.
Oxidizing ability decreases down the group.
Therefore Cl₂ > Br₂ > I₂