Oxidising nature increases from left to right in the order
Cl2< Br2<I2<F2
Cl2< I2< Br2< F2
I2< F2< Cl2< Br2
I2< Br2< Cl2< F2
Oxidising ability of Halogens F2>Cl2>Br2>I2
The correct order of increasing order of oxidising power is