Two routers connect with a serial link, each using its S0/0/0 interface. The link is currently working using PPP. The network engineer wants to migrate to use the Cisco-proprietary HDLC that includes a protocol type field. Which of the following commands can be used to migrate to HDLC successfully? (Choose two answers.)
a. encapsulation hdlc
b. encapsulation cisco-hdlc
c. no encapsulation ppp
d. encapsulation-type auto