Which action is most likely to be classified as an act of plagiarism?

Using a quote without proper formatting is most likely to be classified as an act of plagiarism because it fails to give appropriate credit to the original source in a manner that acknowledges the author's work. Proper formatting generally includes quotation marks, citation, and, depending on the citation style, possibly a reference to the source in a bibliography. When quotes are not formatted correctly, it creates the impression that the words or ideas belong to the writer, thereby infringing on the intellectual property of the original author.

In scholarly and academic contexts, it is crucial to adhere to established guidelines for quoting sources, as these rules help maintain the integrity of the work and respect for intellectual contributions. Without proper attribution, the use of someone else's words can mislead readers about the authorship and originality of the work.