"B" has no errors because the quotation marks are correctly placed - right before the speaker talks and right after they're finished talking. "A" is wrong since the question mark is after the quotation. Like I said ^ you don't put the quotation marks before the ending punctuation. Don't do this:
"Hi",
ONLY do that when quoting someone's quote or some words from a book. I hope this helped and I tried to do as much explaining as I could :) P.S. You might want to put an apostrophe after the "7" in "7s" so it's like "7's". I'm not sure.
