The correct answer is C) search for additional evidence to see which argument it supports.
The other options of the question were A) poll people who live near the location where the historical event happened. B) trust the argument made by the more educated, respected person. D) prefer the simpler argument to the more complex argument.
Two arguments about a historical event contradict each other. Historians determine which argument is superior in that they search for additional evidence to see which argument it supports.
Historians are professionals that have the huge responsibility of transmitting the most accurate representation of history. So when they encounter a situation where two arguments about a historical event contradict each other, they must "dig" deeper, meaning that they have to do more research, get different sources, change the angle of the study, consider more authors, and get the kind of valid evidence that allow them to get the best answer possible.