Which statement is correct regarding BGP route reflectors?

Which statement is correct regarding BGP route reflectors?

A. The route reflectors must have a private AS number.
B. The route reflectors must have an EBGP peering session between each other.

C. The route reflectors must have a cluster ID configured.

D. The route reflectors must have a different AS number than the clients.

Reference: https://www.juniper.net/documentation/en_US/release-independent/nce/topics/example/routing-protocol-bgp-security-route-reflector-configuring-cli.html