Ans. c. Epidemiological transition Epidemiological transition is a phase of development witnessed by a sudden and stark increase in population growth rates brought about by medical innovation in disease or sickness therapy and treatment, followed by a re-leveling of population growth from subsequent declines in feility rates. Epidemiological Transition Epidemiological transition is a phase of development witnessed by a sudden and stark increase in population growth rates brought about by medical innovation in disease or sickness therapy and treatment, followed by a re-leveling of population growth from subsequent declines in feility ratesdeg. This theory was originally posited by Abdel Omran in 1971 Demographic transition Demographic transition (DT) refers to the transition from high bih and death rates to low bih and death rates as a country develops from a pre-industrial to an industrialized economic system. This is typically demonstrated through a demographic transition model.