Answer: We know for sure that there is an established relationship between Casey and Mabel.
Explanation: "She has met Mabel, a kind elderly blind lady who has asked Casey to spend an hour each day helping her around the house".
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.
Mountains observe everything and know everthing
8) D that’s the only one I know for sure. Have a good day
