Which of the following description about the 1+1 protection feature on the client side is incorrect?
A . OTU customer optical layer dual transmission and selective reception;
B . Protect the OTU board and OCh fiber by occupying two operating wavelengths and protecting two wavelengths, and using different routes for transmission;
C . The working and protection wavelengths must be the same;
D . Long application time and wide protection range;
Answer: C