I got 100%, but I also saw some of the same problems with the wording of the answers where I was left thinking along the lines of "well, I know that "b" is the correct answer, but I bet they are looking for me to answer "a"..."
Some of the discrepancies revolve around how things actually work compared to how they officially work. The Queen appointing the PM is a good example of this. She appoints the PM officially, but the reality is the person she appoints is the leader of the party with the most seats, so the one with the most seats does become PM. Tautology reigns supreme!