![](https://cos-cdn.shuashuati.com/pipixue-wap/2020-1230-1107-56/ti_inject-812ce.png)
Which sentence is not correct according to the text? ______.
A.
In dense WDM, the value of ‘dense’ may different for different persons
B.
The core has a higher refractive index than the cladding in a fiber
C.
A receiver needs to de-multiplex a singal when receives it
D.
The main issue on a fiber in transmission is controlling crosstalk effects