Final answer:
Smallpox is the disease that would NOT be considered a reemerging disease as it was eradicated in 1980 and has not shown any new naturally occurring cases.
Step-by-step explanation:
The question 'Which of the following would NOT be considered a reemerging disease? a) Measles b) Mumps c) Smallpox d) Polio' is asking which disease is not currently reemerging in human populations. A reemerging disease is one that was once on the decline but is now showing an increase in incidence. Amongst the options provided, smallpox is the correct answer because it has been declared eradicated by the World Health Organization (WHO) in 1980, and no naturally occurring cases have been reported since. In contrast, diseases like measles, mumps, and polio have seen outbreaks in recent times, particularly in areas with low vaccination rates.