The correct answer is D. Its information may be out of date.
Explanation:
Credibility in sources refers to whether a source can be trusted and/ or believed, when writing a research paper it is necessary to use only credible sources as the credibility of sources is connected to the quality and credibility of your research paper. Credibility is usually related to multiple aspects that include the author, as an expert on the subject is more reliable; the relevance of it for your research topic; the evidence used in the source to support the author's ideas and the date. Regarding the date, it is recommended to use only up-dated articles as knowledge is always transforming and an old article might include information that had been already disproved. Thus, if Janet wants to include an article written in 1976, the article might not be credible because it is too old and the information may be out of date which means more recent researches could have disproved the findings of that article.