well i guess you just have to go through a process of elimination and cross of the list all the topics they have asked in previous years exams - roles of the big 3 at the peace talks, trench warfare, reasons for stalemate etc.
persoanlly i reckon they will ask about impact on women and homefornt and mayb total war.
they can ask about more than one topic cant they?
There is one 10 mark question that require 'your own knowledge' so really its no big deal. It will be a question that centres around one of the topics, a basic knowledge of each of the topics will get you 10/10 easy if you can apply your knowledge.
you can always squeeze the sources for all the info you need...if you're really stuck for own knowledge, look at the other sources they haven't told you to use and use those if they're applicable