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 is option B. The overuse of antibiotics.

Now-a-days use of antibiotics is very common. The antibiotic is used to kill the disease causing pathogen, but the overuse and the senseless use of the antibiotics cause the pathogen to develop antibiotic resistance. once, the antibiotic resistance is developed, the infection cannot be cured by that antibiotic, which is the main cause of increase in the diseases in society.

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.