In the late 1800s, it was proved that all fermentations are the results of microbial activity by*1 pointLouis PasteurRobert HookeCharles DarwinGregor Mendel

The correct answer is Louis Pasteur.

Louis Pasteur was a French chemist and microbiologist whose experiments in the late 19th century demonstrated the role of microorganisms in fermentation. He is well-known for disproving the theory of spontaneous generation, which posited that life could arise from non-living matter. Through his research, Pasteur proved that fermentation processes were caused by specific microorganisms—yeasts in alcoholic fermentation and certain bacteria in lactic acid fermentation. His work laid the foundation for microbiology and helped to establish the germ theory of disease, significantly advancing the understanding of how microorganisms affect both food preservation and human health. Thus, Pasteur's contributions are fundamentally important in the field of microbiology and fermentation science.