i dont think you gave us the choices but epidemiology is the study of health distribution. it determines diseases as well as shapes decisions. essentially they deal with medicine having to do with big diseases and new diseases like cancer.
A sample of urine is added to a substance that promotes the growth of germs. If no germs grow, the culture is negative. If germs grow, the culture is positive. The type of germ may be identified using a microscope or chemical tests.
