Based on what was on the December exam, I would focus on what 501(c)3 and (c)6 orgs can do regarding PACs (which is slightly a trick answer because c3s can't have PACs). You may also want to learn the basics about PACs (i.e. filing requirements with the Federal Election Commission, how much PACs can accept from their association members).
So glad I came across this discussion today - I work at a 501c3 so my knowledge of PACs is minimal at best since we can't have one. I've been stuck on these chapters for a few evenings now, feeling like my prep for the December exam was coming to a grinding halt. Thanks so much for the feedback, Stefanie and for asking the question that's been palguing me Terry!