Which of the following would be considered a Demarc extension?

A patch cable between a cable modem and a wireless router is entirely customer-premises equipment (CPE) interconnecting devices well inside the customer network, not an extension of the demarc.

Patch panel wiring is internal horizontal or backbone structured cabling used within the building's LAN, not related to the service provider demarcation point.

Punch down block wiring is part of the internal structured cabling plant used to terminate horizontal runs inside the building and is not an extension of the carrier demarc.

The demarcation point is the physical boundary where the service provider's network ends and the customer's inside wiring begins, typically at a Network Interface Device (NID) or similar entry point. A demarc extension extends that boundary further into the building by running copper cabling from the NID to a wall outlet or distribution frame, making it practical for customers to connect their equipment without locating gear at the original demarc.