Refer to the exhibit.Which statement describes DLCI 17?()<img src="https://nimg.ppkao.com/2018-07/wangjing/2018072411505115457.jpg?sign=68b12df23b22c14605e94935c0ad955d&t=62d4a076" />
A、DLCI 17 describes the ISDN circuit between R2 and R3.
B、DLCI 17 describes a PVC on R2.It cannot be used on R3 or R1.
C、DLCI 17 is the Layer 2 address used by R2 to describe a PVC to R3.
D、DLCI 17 describes the dial-up circuit from R2 and R3 to the service provider.