In 1890, Robert Koch developed a hypothesis regarding the cause of communicable diseases. He designed an experiment and collected data that supported his hypothesis. Later, his experiment was repeated by many other scientists who used other pathogens and documented similar results that not only supported their hypotheses but also supported Koch's original hypothesis. These many experiments that supported multiple hypotheses regarding the cause of communicable diseases contributed to the development of the

A. theory of evolution.
B. theory of relativity.
C. germ theory of disease.
D. law of gravity.