Using an .xml file to hold the questions and answers, the user is prompted to selected an answer before moving onto the next question and also has the option to go back and change their previous choice. A results page is display on finishing the quiz.
You may notice that all correct answers are in one particular place on each question. Using Fisher-Yates shuffle or a PHP shuffle function would fix this and add some variety to the quiz. But for now feel free to download the demo files and have a play around with the code.