3. Spy vs. Spy. We have captured 5 spies. Their names are A, B, C, D, and E. Here is a summary of what we know: Spy A says he knows 4 others, B 3, C 3, D 2, and E 1. If a spy is lying, he knows more people than he claims. There is no more than one liar. C' is truthing. (a) How can you tell someone is lying? Explain! (b) Show that B must know C.