The Difference Between a SDSL Connection and a ADSL Connection

Multiple Choice

The difference between a SDSL connection and a ADSL connection is

A) ADSL lines have different upload and download speeds.
B) ADSL and SDSL are the same.
C) DSL lines have different upload and download speeds.
D) data transmission and voice transmission can occur at the same time with ADSL and not with SDSL.
E) data transmission and voice transmission can occur at the same time with SDSL and not with ADSL.