What is the name of the technology used on T-carrier leased lines that separates channels by specific time intervals?

A) FDM
B) ATM
C) Frame Relay
D) TDM

D
Explanation: D) T-carrier leased lines use Time Division Multiplexing (TDM), which separates several channels into specific timeslots (time intervals; that is, T1 samples all 24 channels once every 125 microseconds).