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.
The first sentence is correct bc the semicolon divides two independent clauses while replacing a conjunction
Simple sentence because it doesn’t contain any commas but it has a conjunction
