which BGP attribute?

On Cisco IOS and IOS XE Layer 3 MPLS VPN implementations, when redistributing the customer
RIP routes into MP-BGP, the RIP metric is copied into which BGP attribute?

A.
local preference

B.
weight

C.
MED

D.
extended community

Explanation:
https://supportforums.cisco.com/thread/191993
Use the red bgp <asn> metric transparent command to preserve the RIP metrics.
When RIP routes are redistributed into BGP, the route metric is stored in the BGP MED value.
When BGP routes are redistributed into RIP, and the transparent keyword used, the MED value is
copied back as the RIP metric. Without the transparent keyword, the metric value specified is
applied to all the routes.