Hey!
An article is piece of writing included with others in a newspaper, magazine, or other publication. Those can be academic, laboral or just personal.
Now, the subject of an article can automatically limit the timeliness, the audience and purpose. The subject acts like a border to your article and you will have to respect that limit. For instance, every article has a subject, but it will be conditioned by the subject of the writing piece; and, when writing, you have to identify your audicience and it has to be closed relationed with your subjects, because there are some topics for specific public.
In that sense, the only aspect a subject of an article can not limit is A: effectiveness. A topic by itself does not do anything, it is the way of presenting and writing about it. In addition, there is no any way to know if the article will produce the expected effect on the readers just because of the topic.
Hope this helps!
