A historical source is biased when it can be deemed unreliable because the author appears to unfairly favor a particular side or viewpoint.
Bias refers to a historian's perspective being strongly for or against an issue.
Historical bias refers to when the information in the source can be clearly described as unfair, unbalanced, or prejudiced.
Thus, a historical source is biased when it can be deemed unreliable because the author appears to unfairly favor a particular side or viewpoint.
Learn more about a biased historical source at https://brainly.com/question/1614300
#SPJ1