Reference: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/security/a1/sec-a1-cr-book/sec-crc4.html#wp3880782430The command "crypto enrollment peer address" is not valid either.The command "crypto ca identity ..." is only used to declare a trusted CA for the router and puts you in the caidentity configuration mode. Also it should be followed by a name, not an IP address. For example: "crypto caidentity CA-Server" -> Answer A is not correct.Only answer B is the best choice left.