From what I know it basically follows the same pattern as in Unit 1- if there are two topics in the option block, they'll both come up, if there's three, then only two will come up.
So for philosophy in the first block there is religious experience, ontological argument, and atheism and critiques of religious belief. You'd need to pick at least two to revise in depth because if you just did ontological they could just ask about religious experience and critiques of belief.
I don't think there are ones they always ask about, but i'm going to guess for things like objectivity, subjectivism and relativism, they aren't going to ask an entire question on it.
My teacher did say that this year there are more likely to ask questions that combine two different sub-sections.