How to enable CE 1 to learn routes from AS 64430?

As shown in the figure. CE 1 and CE 3 belong to VPN-A, and CE 2 CE 2 4 belong to VPN-B VPN-target VPN-A is 111:1 and that of VPN-B is 222:2 users on different VPNs are not allowed to access each other.

Configuration principles are as follows:

On the backbone network VPNs are not connected to a CE, VPN instance need to be configured on the PE, and an interface on the PE for connecting to the CE must be bounded to a VPN instance. After binding an interface to a VPN instance, you must configure the IP address of the interface Between

PEs, IS-IS is configured for PE interworking. MPLS basic capabilities and MPLS LDP are configured for MPLS LSP establishment, and MP-IBGP is configured for VPN route exchange.

How to enable CE 1 to learn routes from AS 64430?
A . Import IS-IS 200 routes in IS-IS process 100
B . Import IS-IS 100 routes in IS-IS process 100
C . Import BGP routes in IS-IS process 100
D . Import BGP routes in IS-IS process 200

Answer: C