Final answer:
Polar Maritime air masses form in cool, moist regions near the poles, hence off the coast of northern Canada is most likely where a Polar Maritime would form. Regions like Atlanta, the equator, or the tropics are unsuitable for the forming of Polar Maritime air masses.
Step-by-step explanation:
Polar Maritime air masses are most likely to form in regions where the air can become cool and moist over the oceans, generally near the polar regions. The option that is the most convincing for the formation of a Polar Maritime air mass would be off the coast of northern Canada, as the air above the cold waters there can absorb moisture and undergo cooling, creating the conditions suitable for such an air mass.
In contrast, Atlanta, Georgia, is far from the polar regions and typically experiences different air mass characteristics. Similarly, the equator and the tropics are warm regions where the concepts of Polar Maritime air masses do not apply, as air masses in these areas are generally warm and moist, but not of Polar origin.