Although bough, dough and through are all spelled with an 'ough', they are all pronounced quite different from each other (apart from although and dough!). The unfortunate thing about words in '-ough' is that the '-ough' is not always pronounced the same, e.g. in 'cough' it is heard as 'off' but in 'though' it is heard as a short 'oh'.
Spelling is pretty tricky in English, so make sure that you spend time on your spelling. Having said that, this is a really easy quiz and some of the words don't always end in plain '-ough'. Take your time and look at all the answers before choosing. If you struggle with spelling, the best way to learn is to practise, practise, practise! We have plenty of spelling quizzes, not only in our 11-plus, but also in the KS2 and KS3 sections.
Take a look, play a few each day and eventually you'll be a whizz at spelling.