Suppose that \(C\) is false. This means that Ann believes that Bob’s assumption is correct. That is, Ann believes that \(C\) is correct (By (S), Ann believes that Bob’s assumption is \(C\)). Furthermore, by (S), we have that Ann believes that Bob assumes that Ann believes that \(C\) is wrong. So, Ann believes that she believes that \(C\) is correct and she believes that Bob assumption is that she believes that \(C\) is wrong. So, it is true that she believes Bob’s assumptions is wrong (Ann believes that Bob’s assumption is she believes that \(C\) is wrong, but she believes that is wrong: she believes that \(C\) is correct). So, \(C\) is true.