Final answer:
To connect a public line with an internal network, the Main Distribution Frame (MDF) should be used as it serves as the primary hub for incoming and outgoing telephone and data communications.
Step-by-step explanation:
If you need to connect a public line coming into your office with the internal network, the appropriate device to use is a Main Distribution Frame (MDF). The MDF is the primary hub for all incoming and outgoing wiring for telephone and data communications. It is typically used to connect public lines with private networks within a building, ensuring that external services are properly integrated into the internal network infrastructure. An IDF (Intermediate Distribution Frame) is used for further distribution of wires to intermediate or secondary locations after they have been connected to the MDF. The 66 and 110 blocks are types of punch-down blocks used for terminating cable runs and connecting telecom and data lines within the MDF or IDF, but they themselves are not the devices used to connect the public line to the internal network.