Louis Pasteur helped improve public health by A. finding a cure for tuberculosis.
B. improving conditions in hospitals.
C. encouraging new surgical practices.
D. applying germ theory to combat disease.

Pasteurization kills microbes and prevents spoilage in beer, milk, and other goods. In his work with silkworms, Pasteur developed practices that are still used today for preventing disease in silkworm eggs. Using his germ theory of disease, he also developed vaccines for chicken cholera, anthrax, and rabies.

Explanation:

in 550 b.c.e. cyrus the great, the leader of the persians, conquered the medes and united the iranian people under one ruler for the first time. cyrus became the first king of the persian empire and went on to establish one of the largest empires in world.