In a GPON system, which of the following statements about T-CONTs are correct?

All GEM ports must be mapped to T-CONTs.

All ONUs/ONTs connected to the same PON port can use T-CONTs with the same Alloc-ID.

The OLT transmits services upstream in dynamic bandwidth assignment (DBA) scheduling mode.

Carrier that carries services in the GPON upstream direction.