Telephone land lines are part of the __________ and are known as POTS.a.)WWANb.)PPPc.)HDLCd.)PSTN

The correct answer is d.) PSTN.

POTS stands for "Plain Old Telephone Service," which refers to the traditional analog telephone service that has been in use for many years. This service is part of the Public Switched Telephone Network (PSTN). The PSTN is a global system of interconnected telephone networks that allows for voice communication over landline telephone lines. It is considered the traditional infrastructure that underpins telephone communications and includes both circuit-switched and packet-switched connections.

The other options do not relate to traditional landline systems:

• a.) WWAN refers to Wireless Wide Area Network, mainly used for mobile communications.
• b.) PPP stands for Point-to-Point Protocol, used for direct connections between two nodes.
• c.) HDLC is High-Level Data Link Control, a protocol for transmitting data over telecommunication links.

In summary, the answer is d.) PSTN.