The correct answer is A. A serious disease outbreak that infects hundreds of people
In science, the epidemiology is a fill that studies diseases especially in terms of the way diseases emerge and then spread in populations or the way diseases become epidemics. This implies, epidemiologists focus on diseases outbreaks rather than on inherited diseases. Moreover, epidemiology plays an important role in preventive health as well as actions to control epidemics. Considering this, it can be concluded an epidemiologist is likely to study " A serious disease outbreak that infects hundreds of people" because epidemiologists focus on the causes, transmission, and outbreaks of epidemics which are diseases that spread in a population.