Norman's design principles are widely referred to as guidelines for good design. Imagine a situation in which a user has completed an online form to submit their request to a local council. The user has pressed the "Submit" button and saw an empty form appearing on the screen. That got the user wondering whether the information they have entered into the form got sent over the council or whether there was an error which simply deleted all the entries or refreshed the page. Which design principle covers such issues? Feedback Mapping Constraints Visibility Consistency