Which of the following situations is most likely to constitute an instance of plagiarism?

Plagiarism is defined as the act of using someone else's work, ideas, or expressions without proper acknowledgment, leading to the misrepresentation of authorship. The situation that constitutes an instance of plagiarism is one where the individual's work fails to provide proper credit to the original source.

In the situation described, summarizing a published article in 2-3 distinct paragraphs and including this in a paper without a citation clearly constitutes plagiarism. This is because the individual is presenting the ideas and content of another author as their own by failing to acknowledge the source. Attributing ideas or quotations to original authors is fundamental to responsible research practices; without citation, readers might incorrectly believe that the summarizer originated those ideas.

In contrast, the other scenarios involve paraphrasing, quoting directly with proper citation, or summarizing while giving appropriate credit—all of which adhere to the ethical standards of research and writing. Proper citation is crucial in these contexts, as it allows for intellectual honesty and respect for the original authors' contributions.