Asia Has an Intense Monsoon,but North America Also Experiences a Low-Intensity

Asia has an intense monsoon,but North America also experiences a low-intensity monsoon.What causes monsoons?

A) Heating of the polar regions in summer due to long days causes air to flow toward the poles in summer,drawing moisture from warm ocean dominated air masses.
B) The heating of the continent during the summer produces a persistent low pressure over the continent that draws warm moist air masses from adjacent oceans.
C) The oceans warm faster than the continents during the summer and spawn cyclonic storms that move toward the continents.
D) The horse latitude high pressure system breaks down in summer,leading to monsoon moisture in desert locations like southwestern North America and India.