Final answer:
An interview conducted thirty years after the Civil War with someone who fought in it would be a primary source, as it is a firsthand account from the time period under discussion.
Step-by-step explanation:
If we interview a person who fought in the Civil War thirty years after the war, we would consider the interview a primary source. Primary sources are original materials that come directly from the time period to which they refer. They are considered more reliable because they are closer in time to the events being studied. An interview with a Civil War veteran would be a firsthand account of their experiences and as such, is a primary source, similar to diaries, letters, and photographs from the era.
Examples of primary sources include diary entries by individuals who lived during the time of interest, such as a diary entry by a person who lived during the Civil War. Conversely, secondary sources are created after the fact and provide interpretations based on primary sources. Secondary sources often include biographies, history textbooks, and academic journal articles that analyze and discuss primary source materials.