求过路的高手解释。

儒雅文章天下知

A population study based on a "microdata sample" a sample just large enough to allow reasonalbly accurate projections, found that in 1984 there had been a dramatic reversal of a twenty-year tendency toward migration of United States residents older than sixty to small towns and rural redions , both within and across states boundaries. This finding turns out to have been in error. The problem was tha people who had moved to the United States from aborad were accidentally counted as part of interstate migration that year.

Which of the following can be inferred from the passage above?
A. In 1984 the majority of people coming to the United States  from abroad  were over the age of sixty.
B. In 1984 fewer United States residents over the age of sixty changed residence than in any of the twenty years perior.
C. People over the age of sixty who in 1984 came to United States from abroad did not settle predominantly in small towns and rural regions.
D. The microdata sample for 1984 that was used in the demographic study cited was too small to allow any meaningful projections.
E. The twenty-year mentioned in the passage was due chiefly to  moves over relatively short distance, mostly within the same state.

答案是C，不能理解。 我觉得A和E都可以...
还有就是不懂题目到底要表达什么意思...