Well, if we're being thoroughly logical...
the question states which one of the questions is false. That doesn't mean "exactly one question is false". It suggests and it but doesn't state it. It doesn't state that any question is false.
So e) All statements are true is false if there is any other statement that is false.
So as c) is false, e) is false and is a valid answer.
If all other statements were true, statement e) is unresolvable. I think logically such unresolvable statements (statement that are true if they are true and false if they are false) can be declared to be false (or true) by fiat.
So e) is a safe bet. The instructor can not argue it is true. And in fact it is false.