Answer :
The artic air mass would be more viable to change because it is dry and therefore easier to change it. The wet maritime tropical air mass is full of water which has a high heat capacity and therefore changes heat more slowly as well.
The correct answer to this open question is the following.
The type of air mass that you would expect to become modified more quickly is an arctic air mass moving over the Gulf of Mexico in winter.
The arctic air mass comes from Siberia and northern Canada. The dry air of Siberia crosses the North Pole and that is when it spread all over the Noth American territory. Arctic air is colder than Polar air. If you want to know the other air mass classifications, they are the following: highland, continental tropical, maritime tropical, maritime polar, and continental polar.
