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.