Save history editable data RDBMS

Question

I want to make application like testing system. Every question has one or many variant of answers (and one or many can be right). I apologize that tutors and students use my testing system. It means that tutor can make CRUD operations with subject, questions and answers. But in this case appeares one big problem as saving version. For example, I am a tutor and I decide edit some question or answer ( or may be several questions and several answers). When I enter as student, I want to get a list of questions in which I made mistakes but tutor already edited this question and I get wrong information.

Main question: How I can save old versions questions and answers?

Each test has questions and every question has naswers. Tutors can edit/add/delete any of those components. For example, he or she can modify one of the questsion's text, add several questions to a test and edit one of the answers to the question that has just been modified. Any hints how I can handle all this so that I could retreive a version of the test at the exact time in the past?

Here is what I have come up with so far. The solution is extremely complex and I feel there is a better way of doing that.