Typical United States weather pattern show the continental polar air mass moving south towards the Gulf of Mexico. Why does this air mass movement?

A) colder air masses move from north to south
B) continental air mass always move in the direction of the nearest body of water
C) the polar air mask move south to replace the rising maritime tropical air mask
D) the continental Polar air mass is blocked by Maritime air mask on all sides

A) colder air masses move from north to south