Click the Exhibit button. When designing a DWDM system with multiple amplified spans， a pre-amp is needed at Site B to （）.

• A、 offset the OADM loss at site B
• B、 overcome the high multiplexer loss at site A
• C、 amplify signal levels after the high loss through Fiber Span 1
• D、 adjust add channels at site B to be at the same level as the passthrough channels
• E、 ensure that the per channel power is higher than the minimum needed for the post-amp at Site B