Excellent question. As a non-DBA who uses MS SQL a lot, I'd sorta kinda knew that backups would be complete, but the question (and Hugo's expansion on the explanation) makes it clear how that's accomplished.

BTW, I was tickled that the "correct answer" section started with the same words as in the title of one of today's newsletter's featured articles, Bob Hovious's T-SQL: Why “It Depends”.