What does the 1854 plaque commemorate?

The 1854 plaque commemorates a significant event in the history of public health, particularly relating to the discovery of the connection between cholera and contaminated water. Specifically, it honors John Snow's groundbreaking work during the cholera outbreak in Soho, London, where he meticulously mapped cases of the disease and identified a contaminated public water pump as the source of infection. This work laid the foundation for the field of epidemiology and the understanding of disease transmission through water, marking a pivotal moment in recognizing the role of environmental factors in health.

The other choices relate to important events and inventions in their own right, but they do not specifically connect with the context of the 1854 plaque and its significance in public health history. The founding of London and the invention of the pump are historical milestones, while the cholera vaccine, developed later, is related to cholera but not the specific event commemorated by the plaque. Hence, the emphasis on the identification of disease-causing organisms through water contamination is key to understanding the plaque's significance.