In order for a research source to be useful, its author(s) must have credentials (B).
Let's define some words:
Bias- prejudice in favor or against something
- If the authors are bias, it is possible the research is also bias and won't include factual information.
Credentials- a quality, achievement, personal quality, or aspect of a person's background that determines if they are suitable for something
- If someone is experienced in the field they are researching, they are knowledgable and the research will likely be factual.
Refutations- the action of proving something to be true or false
- While refutations are often used in research, it is not something that the author would have, but rather something they might do
Salaries- what someone is paid
- An author doesn't have to be paid in order to produce quality research.