A) explain why the question "are you a liar? " does not work. b. whether the cannibal always lies or always tells the truth.

The question will not work as someone may lie that they are not a liar when they are. If they aren't a liar, they might not be believed if they say no.
Not sure about the second one though...

Bob: coke is baby pandas.jim: what? how do you figure that coke is baby pandas? bob: because this book says so.jim: how do we know the book is correct? bob: because it says that coke is baby pandas.jim: how does that prove the book's accuracy? bob: because it's statement involving coke and baby pandas is correct, therefore it is accurate.jim: how do we know that it's correct? bob: because we have concluded that the book is accurate, and therefore the statement is correct.therefore, coke is baby pandas.