Which of the following reasons may cause ONT failure to discover automatically in GPON network? (Multiple Choice)

Which of the following reasons may cause ONT failure to discover automatically in GPON network? (Multiple Choice)
A . The optical power received by the ONT is greater than the overload optical power.
B . The optical power received by the ONT is less than the sensitivity value
C . The ONT auto discovery function of the GPON port is not enabled.
D . OLT uplink port down

Answer: ABC