The correct option is D Depletion of resources
Population explosion refers to a sudden increase in size of population. Population increase beyond the availability of resource on earth leads to decline in population size on struggle for existence for resources. This will result in major depletion of the resources giving no way to sustainable existence of life on earth. Other odds like famine is usually crop failure caused due to natural calamities and epidemics is occurrence of an infectious disease in a community at a particular time. Wars are the armed conflict among different countries caused generally because of statism. War, epidemics, famines were battled by people and have managed to survive over years.