Ever gotten to the end of a quiz, clicked on 'REVIEW ANSWERS', had an answer ticked as correct, and then got this message?
It's more than likely that, while your answer is correct, it requires more than one correct answer in order for you to move on to the next section.
Look for the questions with the square tick boxes. Like this one...
Like the above example, you may have ticked one of the correct answers...but you need to tick the first two for the question to be right.
Sometimes the question will tell you how many answers you need to select, but other times it's up to you. So, if you get stuck, keep an eye out for those square tick boxes!