A continental polar air mass forms in

a. the Pacific Ocean.

c. the Gulf of Mexico.

b. northern Canada.

d. the desert Southwest ...

Continental Polar air masses are also cold to cool and dry, but are not as cold as the Arctic air masses. Continental Polar air masses form over Canada and Siberia. These air masses bring cold air during the winter and cool, relatively clear, rather pleasant weather in the summer. So it would be northern Canada.