Which Air Masses Influence the Humid Continental Hot-Summer Climates in North

Which air masses influence the humid continental hot-summer climates in North America?

A) Continental polar (cP) in winter; continental tropical (cT) in summer
B) Continental polar (cP) year-round
C) Continental polar in summer (cP) and continental Arctic (cA) in winter
D) Continental polar (cP) in winter; maritime tropical (mT) in summer