Answer:
Because of the transition, Russia suffered with its economy.
Explanation:
With the founding of the Holy Roman Empire would be my best guess
The major threat came from the Seljuk Turks.
Answer:
b.Pasteur’s discovery that disease is spread by bacteria.
Explanation:
The microbial theory of disease or germinal theory of infectious diseases is a scientific theory that proposes that microorganisms are the cause of a wide range of diseases. These small organisms, almost all too small to see them with naked eyes, invade humans, animals and other guests. Its growth and reproduction within the carrier can produce a disease. "Germ" or microbe can refer to a virus, bacteria, protista, fungus or prion. The microorganisms that cause diseases are called pathogens and the diseases they cause are called infectious diseases.
The germinal theory was a scientific discovery made in the second half of the nineteenth century demonstrated by Louis Pasteur and that replaced previous explanations for the disease, such as the miasmatic theory or the theory of humors. Although it was very controversial when it was proposed, it is now fundamental in modern medicine and clinical microbiology, leading to such important innovations as the development of vaccine, antibiotics, sterilization and hygiene as effective methods against the spread of contagious diseases.