Howdy --
Yes, that would be confusing. This is our mistake for referring to them in a question as 'modifiers', when we should have said 'levels', as we do in the book.
But... you will NOT have to worry about this on the real exam, because the exam will NEVER EVER
test you or trick you with recognizing that default is a level and not a modifier, unless you actuall saw code that showed, say, default being explicitly typed in as a modifier.
So when you get questions that say, "Which is the most restrictive access modifier" you can ALWAYS answer the question as though it said "access LEVEL". I promise you that there are no questions on the real exam that will ever use that as an attempt to trick you. In other words, you won't ever have to say to yourself, (as you did with OUR tests), "Ah-ha, I KNOW that 'default' is not technically a modifier, therefore it can't be in this list of correct choices..." If you see a question that says "modifier" assume that this also includes 'level'.
In fact, many people just treat "default" as the 'implicit modifier' as opposed to one of the 'explicit modifiers'. So you can, if you like, think of it as a modifier, as most people do. It's just not a *keyword modifier*. The main reason we make such a point of the difference in the book is to help make it clearer in our explanations. But we really should have followed that all the way through with our questions...
Having said this, I am almost positive that we fixed this in the *real* exam questions, so you probably won't even have the issue. But if there IS one that uses 'modifier' when it means 'level', just ignore the distinction. The only time the distinction would matter on the exam is if you are recognizing that default is not a typed-in modifier, (but in fact is still a keyword used in switch statements), and that's a completely different issue. As long as you realize that 'default' is NOT a typed-in modifier.
Hope that helps, and my apologies for the confusion!
cheers,
Kathy Sierra