<span>The actions of the narrator contradict with the way she describes events.</span>
All of the choices except D (since it's talking about being wary of your own beliefs and bias, not the research on the interviewee) could be correct but i'm assuming this question is talking about the main reason why it is important, so A. would be the best answer in this case.
you should only ask the questions that are the most essential to that interview alone and keep a unbiased mind in order to get what you actually need from the interviewee.
Ancient Greeks would go to an oracle to find out different prophecies. Oracles were said to be able to see the future and were granted prophecies from the gods themselves. Greeks would go to the oracle to try and find out their future or answers to why things were going poorly.