Arrange the definition of epidemiology given by different authors in a chronological order starting from oldest to the latest definition.
A. That branch of medical science which treats epidemics (Parkin).
B. The study of disease, any disease, as a mass phenomenon (Greenwood).
C. The science of the mass phenomenon of infectious diseases (Frost).
D. The study of the distribution and determinants of disease frequency in man (MacMahon).