What germ theory did Louis Pasteur and Robert Koch contribute to in the late 19th century?

Louis Pasteur and Robert Koch's contributions are foundational to the germ theory of disease, which posits that many diseases are caused by microorganisms. Pasteur's experiments disproved the theory of spontaneous generation by demonstrating that microorganisms come from other microorganisms, not from non-living matter. His work focused on how bacteria could spoil food and cause disease, leading to the development of pasteurization.

Robert Koch furthered the germ theory by identifying specific pathogens for specific diseases through his development of Koch's postulates. These postulates provided a systematic method for linking specific germs to particular diseases, such as his work with anthrax and tuberculosis. This scientific approach revolutionized medicine, leading to better understanding and treatment of infectious diseases.

The other theories mentioned do not directly relate to Pasteur and Koch's findings. The theory of spontaneous generation was disproven by Pasteur, while heredity and Social Darwinism pertain to genetics and societal structures, respectively, and do not relate to the germ theory. Thus, the focus on the germ theory of disease accurately captures the significance of the contributions made by Pasteur and Koch in the realm of medicine.