Per the syllabus and study guide: “The two 20 mark questions will come from decision making techniques (“B”), budgeting and control (“C”) and/or performance measurement and control (“D”) areas of the syllabus. The section A questions and the questions in section B can cover any areas of the syllabus.”
So that’s everything except syllabus area A (chapters 1-5) i.e. chapters 6-21 are all relevant to the 20-mark Qs in Section C.