Click the Exhibit button. The exhibit shows a 15454/15216 DWDM system and alarm indications. What are two possible sources of trouble shown in the system?（） (Choose two.)

• A、fiber failure between Sites A and d 
• B、EDFA failure at Site A (clockwise direction)
• C、EDFA failure at Site C (clockwise direction)
• D、15216 multiplexer at Site A (counter-clockwise direction)
• E、OADM pass-through (West "OUT") failure at site D (clockwise)
• F、wavelengths 1 and 3 transmitter failures at Site A (clockwise direction)