Answer:
a. Telnet transmissions are not encrypted.
Step-by-step explanation:
Indeed, since Telnet transmissions are not encrypted, all the information sent, and even the characters typed in the telnet console are sent in clear text.
This is a security issue, since any other device in the same network will receive a copy of the information (packets) sent. For default, all the devices, except for the server expecting to receive the information, will discard the packets. However it is easy to actively listen and keep those packets, wich will contain the information in plain text and human readable.