Why might a historian have a biased opinion about events from the past

from what they learned in school or what thier personal ideas on people and groups of people

the second significant cause of the great migration was the desire of black southerners to escape segregation, known euphemistically as jim crow. rural african american southerners believed that segregation - and racism and prejudice against blacks - was significantly less intense in the north.

answer; i believe that the correct answer is,lies(political rhetoric);