Which three statements about DWDM are true? (Choose three)
A. It allows a single strand of fiber to support bidirectional communications
B. It is used for long-distance and submarine cable systems
C. It can multiplex up to 256 channels on a single fiber
D. It supports both the SDH and SONET standards
E. Each channel can carry up to a 1-Gbps signal
F. It supports simplex communications over multiple strands of fiber
what are the answers ?