I assume you're doing the course on mobile, is that right?
We're aware there is currently a slight technical issue with the quizzes when accessed on mobile.
Fortunately there is a workaround for making the quizzes work on mobile! The best thing to do is enable desktop mode on your mobile device browser.
To do so, click on the menu button at the top right of the browser and select the option Request Desktop Site.
Then, refresh the page.
Can you give that a try and let us know how you get on?
Please note this method may not always work. The alternative is to complete the quiz on a computer. It should work there.