Which of the following best describes primary sources?

Primary sources are best defined as the initial evidence related to a subject because they provide direct or firsthand accounts that have not been altered or interpreted by others. Examples include original documents, such as letters, photographs, government documents, diaries, and firsthand narratives of events. These sources are invaluable for research as they offer direct insight into the topic being studied and enable scholars to analyze the primary data without the influence of later interpretations or secondary analyses.

The other choices describe elements of secondary sources, which are derived from primary sources and involve analysis, summarization, or discussion of those initial pieces of evidence. For example, compilations of analyses or summaries would incorporate interpretations of primary data rather than present it directly, thus falling outside the definition of a primary source.