What does qos pre-classify provides inregardto implementing QoS over GRE/IPSec VPN tunnels？（）

• A、 enables IOS to copy the ToS field from the inner （original） IPheader to theouter tunnel IP header
• B、 enables IOS to make a copy of the inner （original） IP header and to run a QoS classification before encryption， based on fields in the inner IP header.
• C、 enables IOS to classify packets based on the ToS field in the inner （original） IP header
• D、 enables IOS to classify packets based on the ToS field in the outer tunnel IP header
• E、 enables the IOS classification engine to only see a single encrypted and tunneledflow to reduce classification complexity