1. The untypical way for a person to catch a disease is A. from pathogens in boiled water. Boiled water doesn't contain these - boiling a liquid makes it clear from any bacteria there may be.
2. The option which is not important to determine the cause of a mysterious disease is D. how wealthy the diseased people were, whereas all the other options are quite important and relevant.
<span>b. It is an important source of fuel for sprints and bouts of high-intensity exercise.</span>
The answer is "Childhood Vaccines"