What distinguishes IP telephony from standard analog telephony?

What distinguishes IP telephony from standard analog telephony?

A.
IP telephony uses IP addressing to provide a single dedicated path through a circuit-switched network.

B.
IP telephony uses IP addressing to enable two-way voice transmission over a packet-switched TCP/IP network.

C.
IP telephony uses TCP/IP to ensure that voice packets are given priority throughout the network so that conversations arrive intact.

D.
IP telephony uses IP addressing to establish a single dedicated path through a packet-switched network.