Which Is CORRECT

Multiple Choice

Which is CORRECT?

A) The Optical Carrier (OC) is an ITU-T international standard.
B) DS (Digital Signal) speeds are multiples of 64Kbps, data rate of a voice call.
C) Optical Carrier (OC) speeds are multiples of 155 Mbps.
D) The STM (Synchronous Transport Module) standard was introduced for twisted pairs.
E) Both DS and OC standards were introduced at the same time.