What two descriptions best define DWDM？ （） A:  a WDM system that is compatible with EDFA technology B:  an optical technology for transmitting up to 16 channels over multiple fiber strands C:  an optical technology for transmitting up to 32 channels over multiple fiber strands D:  a technology for transmitting multiple optical signals using less sophisticated transceiver designthen CWDM E:  a technology for transmitting more closely packed optical signals using more sophisticatedtransceiver designs than CWDM