Three friends are playing a game of memory, there are a total of 20 cards with 10 card pairs. They try to make the most pairs in a row, after everyone had a turn they make the following statements:
Person a: "I've made 10 pairs in a row, I'm perfect".
Person b: "I've made 9 pairs in a row, I'm not the best but I'm good enough".
Person c: "I've made 5 pairs in a row, I could do worse".
One person is lying, who is it?