Which two QoS fields should be used by R1 and R2 to classify the traffic sent from PC1 to Server1? (Choose two)

Which two QoS fields should be used by R1 and R2 to classify the traffic sent from PC1 to Server1? (Choose two)

A.
CoS

B.
IP DSCP

C.
DE bit

D.
priority bits

E.
IP precedence