what type of messaging, if any, occurs between R3 and R4?

After the network has converged, what type of messaging, if any, occurs between R3 and R4?

A.
No messages are exchanged.

B.
Hellos are sent every 10 seconds.

C.
The full database from each router is sent every 30 seconds.

D.
The routing table from each router is sent every 60 seconds.