Where are the examples?..
It was determined from chemical analysis and observations by the EPA in the 1970's that the Love Canal in New York is considered to have "contaminated with toxic chemicals." Due to these, the canal was furthermore restricted to any human activities taking place due to the hazards it would produce.
I would say either A or C, but i'm not positive, my research didn't tell me much, sorry!
Two of the most common problems that many European colonists faced were 1) a lack of food due mostly to improper knowledge of farming, and 2) hostile native populations.
