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.
Answer:
Because all squares must have parallel sides
Explanation:
Hope this helps :P
Answer:
The type of metal sheet used is your independent variable
