What is the purpose of a route target community in a Layer 3 VPN?

What is the purpose of a route target community in a Layer 3 VPN?

A.
The community value is used to identify routes that should be imported by remote PEs.

B.
The community value is used to determine valid remote devices when signaling a Layer 3 VPN.

C.
The community value is used to identify the source of incoming routes.

D.
The community value is used to determine transit devices when signaling a Layer 3 VPN.

Explanation: