Heyy!!
I am standard english and not great at it but as it is AOS i will share my two cents worth....
Firstly, I recommend checking out Mada438 article on
playing devils advocate. hopefully this will help.
Secondly... To what extent is your personal response to the question.
To add onto D.P's answer...
To what extent is a judgement; so your thesis should focus on that judgement. Is it a partial, moderate or significant extent?
Once you make that judgement, your arguments and analysis are centred around proving that your judgement (e.g a partial extent) is correct.
Remember that this judgement is never wrong, so long as you back it up! and vice versa, it's not the only correct one. Other people will make different judgements, argue that judgement and still be correct.
Thirdly.... your related text doesn't have to support your prescribed text it just has to linked to the syllabus...
Not sure if this helps or if it is correct..... for a question like that a simple thesis could be:
Whilst discoveries can be as a result of careful and deliberate planning, typically discoveries are evoked by curiosity and wonder (sorry, very on the spot)... remember to always back-up your thesis whatever it is....
all the very best....