The role of a catalyst is to change: 

1. Gibbs energy of the reaction
2. Enthalpy of reaction
3. The activation energy of the reaction 
4. Equilibrium constant
HINT: Catalyst do not effect thermodynamic properties of reaction.
Explanation:
The role of a catalyst is to change the activation energy of the reaction. This is done by either increasing or decreasing the activation energy of molecules.
It only alter the rate of reaction but it didnot effect the thermodynamic properties of reaction.