One Possible Reason for the Increase in Species Richness Toward

One possible reason for the increase in species richness toward the tropical latitudes is that

A) net primary productivity is lower in the tropics than in temperate climates.
B) large-scale disturbances are more prevalent in the tropics than in temperate climates.
C) small-scale disturbances are more prevalent in the tropics than in temperate climates.
D) tropical climates are less variable than temperate climates.
E) tropical climates are more variable than temperate climates.