D. The first appearance tells when the article was produced, while the second appearance tells when the article was cited by the essay writer.
Explanation:
However the citation is missing the author's name, yet as per the question, the dual occurrence of the year is deliberate. The first appearance is hinting towards the production or publishing year of the essay while the second one tells that the version used by the author. The appropriate citation is crucial to understand the sources used by the author and assists in referring to it for a better understanding and evaluation of the text.