D is correct. This is the correct command, and must be entered in Line Configuration mode. A, B, and C are incorrect. A and B are incorrect because no telnet is not a valid IOS command. C is incorrect because it is the correct command, but it’s in the wrong configuration mode Solution D is correct. This is the correct command, and must be entered in Line Configuration mode. A, B, and C are incorrect. A and B are incorrect because no telnet is not a valid IOS command. C is incorrect because it is the correct command, but it’s in the wrong configuration mode.