The role of a catalyst is to provide an alternative path by forming an activated complex with lower activation energy without changing the enthalpy of reaction.

Activation energy is required to start the reaction by making an activated complex.

A surface is provided by a catalyst for reactants so that activated complex can be achieved with lower activation energy.

Only option (iii) talks about activation energy hence it is correct.

No change in Gibbs free energy, so option (i) is wrong

No change in enthalpy of reaction, hence option (ii) is wrong.

The equilibrium constant remains the same with or without the use of catalyst, hence option (iv) is also wrong.