The correct answer is "sample." ideally these are randomly selected observations as to prevent bias. we can assume the samples that are unaffected by systemic bias represent the population due to rules of the normal distribution.
It decreased and very significantly so!
Most of native Americas died of diseases brought by Europeans; but some were also killed directly by the Europeans. Many also mixed with the Europeans (by marriage or rape...) so there was also a mixed indigenous-white population.
ps. C and D is essentially the same answer
Nationalism was a great cause of World War one because of countries being greedy and not negotiating. Nationalism shows you are proud of your country and want it to be the best. A lot of causes all linked back to countries all wanted to be better than each other.
