The method a historian would use when considering an author's feelings or actions that favor one thing over another is referred to as C. bias.
Bias in historical analysis involves recognizing the subjectivity that an author or source may have due to personal beliefs, social background, or the historical context in which they were writing. Historians critically assess sources for signs of bias in order to understand how an author's perspective might influence their interpretation of events, subjects, or people. This assessment helps historians build a more nuanced understanding of history, taking into account the various influences on the creation of historical narratives.
While point of view (A), frame of reference (B), and historical context (D) are also important concepts in historical analysis, bias specifically addresses the idea of favoritism or partiality in an author's perspective.