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）

A. All "Add" channels require uniform power levels.
B. The flexibility of wavelengths per OADM is limited.
C. It is easier to balance "Pass-Through" and "Add" channels.
D. There is lower pass-through loss using multi-channel OADMs.
E. You can extract a single channel without dropping other channels.

A. 15 dB
B. 17 dB
C. 21 dB
D. 26 dB
E. 27 dB

A. none
B. one
C. two
D. three
E. four

A. The ONS 15216 OADM can be provisioned to add/drop one， two， or four channels via Cisco Transport Manager （CTM）.
B. The ONS 15216 OADM consists only of a four-channel module， and the number of ports utilized determines whether it is a one， two， or four channel OADM.
C. Three separate OADM modules are available for one， two， and four channels. The wavelengths to be dropped and added are programmable via Cisco Transport Manager （CTM）.
D. The ONS 15216 OADM consists only of a single-channel module. Two-channel and four-channel support is available by stacking the single-channel module.
E. The ONS 15216 OADM is available in one， two， four channels.  There are 32 single-channel OADM modules， 16 two-channel OADM modules， and 8 four-channel OADM modules.