Cu²⁺
Ag⁺
Fe³⁺
I₂(s)
Higher the reduction potential, better is the oxidizing agent. Now, the reduction potential decreases in the order: Ag⁺|Ag (+0.80V) > Fe³⁺|Fe²⁺ (+0.77V) > I₂(s)|I⁻ (+0.54V) > Cu²⁺|Cu (+0.34V). Hence, Ag⁺ is the strongest oxidizing agent.