Which statement describes the function of a trust boundary? Select the best response.

A.
Trust boundaries determine whether certain types of traffic can pass.

B.
Trust boundaries are a point in the network where decisions about CoS markings on incoming packets are made.

C.
Trust boundaries are a point in the network where QoS functionality begins and ends.

D.
Trust boundaries are points in the network where Layer 2 CoS markings are converted to Layer 3 DSCP or IP precedence markings.