The correct option is: VAPORIZATION AND CONDENSATION.
Matters have the ability to change from one state to another state, this is called state transition. In the question given above, the carbon dioxide, which Uyen's was breathing out came in form of vapors and forms a cloud by condensing. Condensation is the process by which water droplets are formed when a vapor from comes in contact with cold surfaces. In the question given above, the vaporized gas condenses when it comes in contact with the humid air.