where the customer uses OSPF how is the OSPF route cost propagated between sites?

In an MPLS VPN where the customer uses OSPF how is the OSPF route cost propagated between sites?

A.
A BGP extended community is used to pass the OSPF cost.

B.
The cost is passed transparently through area 0.

C.
The cost is configured using the default metric parameter.

D.
The BGP MED is used to pass the OSPF cost.