Which Is Not a Method of Connecting BRI ISDN into the Customer

Which is not a method of connecting BRI ISDN into the customer?

A) Equipping a computer with a TA that also contains a network terminal network terminator.
B) Connecting the ISDN line into an external TA that is equipped with a U interface into which you plug in the ISDN line.
C) Using a multiplexor or a PBX.
D) Bringing the ISDN line into a NTU.