Which of the Following Statements Gives the Main Reason Why

Multiple Choice

Which of the following statements gives the main reason why the wintertime mP air masses are less common along the North American Atlantic coast than along the Pacific coast?

A) The water is warmer along the Atlantic coast.
B) The prevailing winds aloft are westerly.
C) The source region for mP air on the Atlantic coast is western Europe.
D) The water is colder along the Pacific coast.