Which of the following should be noted when performing hardware loop on optical inter

Which of the following should be noted when performing hardware loop on optical interface through fiber？()

A.Never look straight at output optical interface or tail fiber end surface that connects with it.

B. First you must disable laser output to avoid too strong output power burning down tail fiber end face.

C. Use an optical power meter to measure input interface power to avoid receiver burning down due to overload.

D. If there are no attenuators, loosen the receiver and tighten the transmitter to prevent optical input from overloading.