What enables Quality of Service $($QoS$)$ in a Multiprotocol Label Switching $($MPLS$)$ network?

Group of answer choices

b$)$ The CoS identifier

a$)$ Type of Service $($ToS$)$ bits in the IP packet header

c$)$ A virtual routing and forwarding $($VRF$)$

d$)$ Session Initiation Protocol $($SIP$)$ trunking