The correct answer is B) a letter from a soldier who fought in the Napoleonic Wars.
All of the following are examples of secondary sources EXCEPT "a letter from a soldier who fought in the Napoleonic Wars."
A secondary source is based on another source. In this case, the letter was written by a soldier that participated in the war, so it is considered a primary source.
A secondary source could be a book written about the story of that letter, or interviews with scholars that are experts on Napoleon Bonaparte, or articles of magazines about the wars in Europe during the 1800s.
