What is a primary source?

A primary source is defined as an original document or firsthand account of an event or topic. This means it provides direct evidence or firsthand testimony about the subject in question, allowing researchers and historians to gain insight from the perspective of those who experienced the events directly. Examples of primary sources include diaries, letters, photographs, original research articles, and official documents.

The other options represent secondary forms of information. A summary written by a witness, while containing firsthand accounts, is considered a secondary source because it interprets or summarizes the primary experience rather than presenting it directly. Reference materials used for research might include encyclopedias or textbooks, which compile information from various primary and secondary sources. Lastly, a review of historical events by an author represents another layer of interpretation and analysis, making it a secondary source as well. Therefore, the correct answer accurately identifies primary sources as original materials that provide direct insight into the topic being studied.