PAP, CHAP, MS-CHAP, and EAP

Four methods of authentication and authorization are discussed in this video. The four methods are password authentication protocol (PAP), challenge handshake authentication protocol (CHAP), Microsoft CHAP (MS-CHAP), and extensible authentication protocol (EAP). While watching this video pay attention to the method of authentication used by each protocol. Which method is the least secure and why? Which method is proprietary?