How is route target (RT) information attached to a VPNv4 route?

How is route target (RT) information attached to a VPNv4 route?

A.
Using the MPLS Label field.

B.
Using the MPLS EXP bits.

C.
Using route tags.

D.
Using Extended BGP communities.

E.
Using the Route Distinguisher (RD) field.