Answer:
The correct answer will be option- C
Explanation:
A research journal is considered as the reliable or credible source of the research as the research articles published in the journal are always verified by the peer-group which includes the scientists.
The peer-group verifies the credibility of the research paper by checking and correcting the steps of the scientific method and checking the eligibility of the collected data and the conclusions drawn from it.
Therefore, Nick should use a medical journal published in 1982 as the credible source for him and thus option- C is the correct answer.