Answers to all Bing Quizzes hide in the source code of the quiz page. You need to just open the page's source code and search for a particular term to get the answer. Different quizzes have different search terms.
If you are looking for the answers to the Supersonic quiz, you need to search for the term "isCorrectOption" in the source code. All the options with "isCorrectOption=True" are the correct answers.
You can find more details here.