You attach six routers (R1, R2, R3, R4, R5, and R6) to a single Ethernet LAN and configure the routers with addresses in the same subnet. You do not modify the default priority of any router. R1 is chosen as the designated router and R2 is chosen as the backup designated router. How many full adjacencies does R3 have?

A.
0

B.
1

C.
2

D.
5