Not understanding Le Chatelier's principle on this question

Here is my question:

Given FeO (s) + CO (g) <---> Fe (s) + CO2 (g); endothermic reaction


If the reaction vessel's pressure is increased, P CO2/ P CO would? (P= pressure)

1. Increase
2. Decrease
3. Remain the same


I originally thought it would increase, but the correct answer is remain the same. Is this because CO2 and CO have a one to one mole ratio? Not sure about the logic on this one.

it would remain the same because they are both gases. if you increase the pressure you are increasing the collision of FeO with CO AND the collisions of Fe with CO2
nothing changes