Pick the 4 valid ATM Cell Header fields:
A.
GFC-4 bits of generic flow control
B.
Forward-explicit congestion notification(FECN)
C.
VCI-16 bits of virtual channel identifier
D.
CLP-1 bit of congestion loss
E.
HEC-8 bit of header error control
F.
ATM Discard Eligibility(DE) bit