Final answer:
Without the article, it's not possible to provide an accurate answer to which words are synonyms; generally, 'Relationship' and 'Link' are synonyms, as both imply a connection, but the correct answer is dependent on the context of the article.
Step-by-step explanation:
The question provided does not contain enough context to determine which two words are the closest synonyms. To identify synonyms, we need to know the meanings of the words in the context of the article. For general purposes, however, the closest synonyms from the options given would typically be Relationship and Link since both words can refer to a connection between two things or concepts. Meanwhile, if the article was discussing research designs, the closest synonyms could be Retrospective and Prospective, which relate to looking backward and looking forward in time, respectively, in the context of studies or analyses.
Without the article for reference, however, we cannot accurately determine the correct pair of synonyms. Thus, the final answer to this question cannot be provided without additional context from the article. This answer requires the content of the article to accurately match the synonyms in question. Synonyms are highly context-dependent, and a word can have different synonyms based on the particular meaning it takes on within a text.