Final answer:
A thesis statement is the term that best describes the one-sentence declaration of what the argument will be. The term that best describes the one-sentence declaration of an article's argument is a thesis statement. It clearly states the topic, writer's position, and the reasons that will be supported in the essay, typically presented as the last sentence of the first paragraph.
Step-by-step explanation:
The term that BEST describes the one-sentence declaration of what the argument in Billy’s article will be is a thesis statement. A thesis statement is a critical element in argumentative writing, providing a clear indication of the writer's position on a debatable issue. Not only does it state the topic and the stance the writer is taking, but it also outlines the reasons that will be discussed to support this position throughout the essay.
Typically, writers introduce the issue and assert their thesis statement as the last sentence of the first paragraph, ensuring the issue has at least two debatable sides. The thesis statement should be formulated as a declarative sentence that is concise, specific, debatable, and understandable. It serves as a roadmap to guide readers through the writer's argument, making clear what stance the writer is taking and what the paper will discuss.