请教GMAT逻辑大全Test16-15

In the course of her researches, a historian recently found two documents mentioning the same person, Erich Schnitzler. One, dated May 3, 1739, is a record of Schnitzler’s arrest for peddling without a license. The second, undated, is a statement by Schnitzler asserting that he has been peddling off and on for 20 years.

The facts above best support which of the following conclusions?

(A) Schnitzler started peddling around 1719.

(B) Schnitzler was arrested repeatedly for peddling.

(C) The undated document was written before 1765.

(D) The arrest record was written after the undated document.

(E) The arrest record provides better evidence that Schnitzler peddled than does the undated document.

答案是C，可是我怎么也不理解1765这个年份是怎么出来的。我觉得选D还有些道理

请赐教，谢谢！

一件事：1739年被抓

另一件事：peddle 20年

两件事合并一起看，这是个时间段的问题

取这个时间段两端的极值：

假设，他刚开始peddle就被抓，那么1739+20=1759年之后他就不再peddle了

     他peddle了20年才被抓，那么1739-20=1719年，在这之前他没有peddle

那么，这个undated document 必然在1719——1759之年喽，也就是C选项所说的在1765年之前

我的个人理解，希望有所帮助