Even though synonyms generally share the same meaning, they might not apply in the same context. So, if you want to use one specific word you should do that instead of trying to find a synonym that doesn't quite fit into the context you've established. An example is if you want to use the sentence "I was mad", meaning "I was angry", you could look for a synonym. One synonym is "absurd". However, this is a different type of mad, meaning crazy instead of meaning angry. "I was absurd" has an entirely different meaning than originally intended. This is why you should always double check the contextual meaning of the synonym you want to use.
I'd go with B - Article. There are hundreds of good examples for the answer being B. For example, "a book" ('a' is an article - 'book' is a noun), "an apple" ('an' article - 'book' noun). Those are just the simple ones.
