Explain the Most Likely Reason Why Smallpox Was Successfully Eradicated

Explain the most likely reason why smallpox was successfully eradicated but rabies probably never will be.

A) Smallpox was only found in humans; rabies is found in numerous animal reservoirs. We cannot reasonably eliminate rabies in all of the animal reservoirs that exist.
B) It was far easier to vaccinate the world population against smallpox than against rabies, due to the lower number of injections required for the smallpox vaccine. It becomes a compliance issue.
C) Since there are very few cases of rabies each year, there is little financial incentive to push health organizations to eradicate the illness through worldwide vaccination.
D) The symptoms of smallpox are easier to identify than the symptoms of rabies, so some carriers of rabies are not accurately diagnosed. This can lead to asymptomatic carriers present within the population of susceptible individuals, spreading the virus.
E) Smallpox was eradicated because anyone who got the disease died from it, so at some point there was no reservoir for the virus.