Which of the following best describes the function of a PDU session flow classifier?

A. An SMF that dynamically inserts and removes uplink classifiers (UL CL) at the UPFs.

B. An SMF that dynamically inserts and removes UL CL at the UE.

C. A UPF that terminates the N6 interface towards the data network.

D. A UPF that filters uplink traffic according to UL CL rules provided by the SMF.

Reference:
https://www.metaswitch.com/knowledge-center/reference/what-is-the-5g-user-plane-function-upf