Which is the best example of a primary source document useful in the study of history?

Which of the following was a difficulty faced by the ottoman empire in the 1700s and 1800s?   a.  financial independence      b.  lack of trained artisans      c.  refusal to trade with other nations      d.  rebelling ethnic groups

According to greenville why does great britain have a large debt and who should pay that debt? ?

Which of these were effects of mass production techniques used during 1920s