When I first solved it I selected B but when I sat down to type it down I spotted 3-4 and thought that was the one I had gone with originally. But in the solut

When I first solved it I selected B but when I sat down to type it down I spotted 3-4 and thought that was the one I had gone with originally. But in the solution they motivate the specific selection of B by stating that in the provided lists of pairs, the pairings are all with the greater number first. Hence actually what I typed above is incorrect and the correct answer is B. Sorry about that :(