Answer:
When evaluating a source for bias, the researcher should always avoid first-person source material. The correct option in order to complete the sentence is C.
Step-by-step explanation:
When evaluating a source for bias, we can never trust in one person's material because it can't be objective. It is always an opinion based on personal experiences, so it wouldn't be accurate to use it. We always have to make sure that our source is imparcial and that his/her information is based on facts and not subjective opinions.