Why would a historian find this to be a biased source of information?

First, historians sometimes misinterpret evidence, so that they are not justified in asserting that the inferences they draw about what happened in the past are true. ... They are only biased if they occur because the historian wants the outcome she has produced, normally to further certain interests that she has.

Explanation:

the correct option is: a liberal.

the kind of person that is most likely to hold a left-wing political ideology is liberal because they have in common that they support human individual rights and liberties. also, they both have politically and economically centrist.

moreover, a liberal believes that everyone should have equal rights as well as opportunities to succeed in life, and the freedom to make their own decisions as long as they don't attack the rights of other people. all people deserve the same opportunities and basic needs.