The Type of Weather System Known as a "Mid-Latitude Cyclone

The type of weather system known as a "mid-latitude cyclone" cannot form over the tropical ocean because:

A) surface temperature contrasts are not large.
B) the ocean surface has a lot of waves.
C) the Coriolis force is weak in the tropics.
D) both (a) and (b)
E) both (a) and (c)