The correct answer is A) evidence they collect.
The other options of the question were B) interviews with citizens.
C) opinions they have heard. D) historical novels.
Historians base interpretations of past events on evidence they collect.
That is why it is of the utmost importance that historians do research using valid sources of information. It can be primary or secondary sources that validate the time, the place, the characters that were part of an event or incident. Otherwise, they put their credibility at risk.