When WCCPv2 is running on a switch or router, what does it use to redirect traffic to a Cisco WAE?

When WCCPv2 is running on a switch or router, what does it use to redirect traffic to a Cisco WAE?

A.
NBAR

B.
GRE tunnels or Layer 2 direction

C.
MPLS tunnels or Layer 2 direction

D.
Layer 4-7 inspection