I'm taking some online quizzes in a specific subject and I've faced the following question
Which statement is false?
4- No statement is false.
5- All statements are false.
The sentences 1,2, and 3 are true. I've chosen 5 and I got incorrect answer and the teacher said the correct answer is 4. It seems to me the way the question is formulated doesn't test my knowledge in the subject which pisses me off. I would like to know if the question from linguistic point of view is correct or valid so that I can file a claim.