Which accurately describes a letter written during the time a historical event occurred?
a. effective secondary source document
b. too biased for historical evidence
c. too focused for historical evidence
d. unreliable narrative source
e. useful primary source document

The correct answer is E. Useful primary source document

Explanation:

In history, a source refers to any source or material that provides information about an event of the past. This source can be classified as primary sources if they were written during the historical event studied and therefore are a first-hand account of the event or as secondary sources if the source uses primary sources to create a new source. Also, sources are considered as useful or effective if they provide information about a historical event. Therefore, a letter written during the time a historical event occurred would be considered as a "useful primary source document" because this document is a first-hand account of the historical event being studied (primary source) and also provides information about it, which make it a useful document.

d) a constitutional amendment

nothing certain is known about what happened, but it seems that the country declined gradually, perhaps due to bad government, or, more likely, due to a series of bad harvests, which resulted in widespread and recurrent famine.