In Mexico, it's important for foreigners to not drink the water because they might get:a)Amoebic dysentery b)malaria

I find the question and the choices to be oversimplified
and cliched. Firstly, what exactly do "foreigners" mean? From the perspective of the
person who is asking the question, would someone from Nicaragua be considered as much as
a foreigner as someone from the United States while visiting Mexico? Furthermore, who is
the one formulating the question and for what
purposes?

Many people who travel from one region to
another, even within the same country, develop new diseases or a strong ailment from
viruses or bacteria strains to which an individual has not yet developed full immunity.
For instance, people who move from Toronto to Vancouver, and vice-versa, tend to get
unusually strong colds the first year of having settled in the new region. With regard
to "the water" in Mexico, all cities in Mexico have potable water that is up to
international standards. Are foreigners who are getting sick mostly those who go to
questionable resorts designed for international tourists, or are they purchasing food
and beverages from street vendors or restaurants that cut corners in terms of
hygiene?

This leading question also lacks grammatical
logic. People need to drink water on a daily basis. Not drinking water while visiting a
foreign country (for several days at least) would be far more harmful (and deadly) than
drinking it.