(hope this helps)
middle-distance running, in athletics (track and field), races that range in distance from 800 metres (roughly one-half mile) to 3,000 metres (almost 2 miles).
This warning was most likely issued to prevent people from bringing SARS to the USA when they come back from visiting the countries. So the answer is pretty much to stop the spread
You do it before a lab so as to prevent contamination of the materials. You might have things on your hands that might contaminate the experiment and the research. You do it after because you don't want to have things from your experiments on your hands because that can be extremely dangerous.
It's choice A i truly believe.
