The Maritime Tropical Pacific (MT)and Maritime Tropical Gulf and Atlantic

The maritime tropical Pacific (mT) and maritime tropical Gulf and Atlantic (mT) air masses are

A) very different because the Pacific air mass is very unstable and the Gulf/Atlantic air mass is usually stable.
B) both less active during summer months.
C) both usually extremely unstable.
D) different from one another because the Pacific air mass usually has lower specific humidity than the Gulf/Atlantic air mass.