<span>If John Snow was investigating a cholera outbreak today, he would have access to modern scientific equipment that would allow him to pinpoint the source of the outbreak, such as microscopes with enough power to see the microbes. Additionally, he would know of modern theories of disease and infection, and so would have a better framework to understand the evidence he gathered. The combination of these factors would allow Snow to much more quickly and effectively discover the source of the outbreak.</span>
I'd argue the nervous system because you sense pain through your nerves and when you realize something is poking you bam your nerves recognize it and tell your brain "UH OH CHEIF THERE'S A TACK" and you pull it out.
