CAB is for Citizens Advice Bureau. The quiz is sent to every Bureau in the Country in November with 100 questions. Answers have to be in by the middle of January, so plenty of tome for research.
Further to Coyote's response, a lot of people spend some time researching the answers to the CAB quiz questions. To then see a lot of the questions posted on quiz websites without that person having done a simple search gets quite frustrating.