Answer:
The system will shift to the right (Forward).
Step-by-step explanation:
Based on the equilibrium:
2CO(g) + O2(g) ⇄ 2CO2(g)
If the amount of O2 is increased: The equilibrium will shift to the right trying to decrease this concentration following the Le-Ch principle that says:
A change in an equilibrium will be counteracted by the system producing a response that restore the initial state.