Why Are We Concerned at All with Monitoring Emerging/reemerging Diseases

Why are we concerned at all with monitoring emerging/reemerging diseases?

A) These represent growing threats to human health that will require new scientific research and resources to effectively combat.
B) Because globalization (greater trade and travel between countries) leads to more chances for spread of illnesses into new areas and populations.Monitoring these illnesses will help us to protect people.
C) Because the speed of travel has increased greatly.With increased speed of travel,it is far more likely that a serious pathogenic threat from one area of the world can spread rapidly across the globe in a very fast manner.We need to monitor the occurrence of these illnesses to try to protect populations.
D) All of the above.