Which ISDN device converts the four-wire BRI signals from an S/T interface into two-wire signals of a U interface?（）

A.NCP
B.HDLC
C.LAPB
D.LAPD

A. To ma a known IP address to a MAC address
B. To map a known DLCI to a MAC address
C. To ma a known MAC address to an IP address
D. To ma a known DLCI address to a IP address
E. To ma a known IP address to a SPID address
F. To ma a known SPID address to a MAC address