When studying history, it is important to understand bias and its possible impact on a historical narrative. Historians are a product of their various opinions and backgrounds, and the student of history must keep this in mind when studying a secondary historical source. One historian, for example, might place emphasis on the social causes of a historical event while another historian might argue for economic causes. These two points of view would have the potential to greatly impact the historical narrative told by these historians.

Which of the following is the main point of the passage used here?
A.
There can only be a few causes of any particular historical event.
B.
Social causes of events are usually overshadowed by economic causes.
C.
Bias should be excluded from historical analysis as much as possible.
D.
A historian's narrative will reflect his or her own opinions.