Which PPP subprotocol negotiates authentication options?

A.
SLIP

B.
NCP

C.
ISDN

D.
LCP

E.
DLCI

Explanation:
LCP: A method of establishing, configuring, maintaining, and terminating the point-to-point connection.
Link-establishment phase LCP packets are sent by each PPP device to configure and test the link. These packets contain a field called the Configuration Option that allows each device to see the size of the data, compression, and authentication. If no Configuration Option field is present, then the default configurations are used.