Explanation : Primary sources are documents, images or
artefacts that provide firsthand testimony or
direct evidence concerning a historical topic
under research investigation. Primary sources
include historical and legal documents,
eyewitness accounts, interviews, surveys,
fieldwork, collective questionnaire, email
communication. In the natural and social
sciences, primary sources are often empirical
research in which an experiment is performed
or a direct observation is made; its results
being typically included in the report.