Answer:
c. Epidemiological research
Step-by-step explanation:
Epidemiological research -
The term Epidemiology , refers to the study involving the study of diseases over the wholesome area of population of a specific organism , which could be humans or animals , involving the cause , effect and symptoms of the disease .
The people doing Epidemiological research , find the factors which can lead to the disease and the factors to help people fight against the disease .
The disease could be smallpox , as it can spread from person - to - person and hence is a cause of concern .