Which of the following is a contributing reason behind emerging disease?

a. The lack of evolution in hostsB. The overuse of antibioticsC. The absence of migration or travel in organismsD. The lack of evolution in pathogens

The correct answer should be B. The overuse of antibiotics. Since antibiotics as their name says kill biotics, that is, they fight against bacteria, they were used a lot and bacteria started developing resistance to them which is a common thing. Since it's difficult to find new types and the trials last long, new diseases are emerging faster than we can create medicine for them.