Per the command output, with how many routers is router R4 full adjacent over its Gi0/1 interface?

R4# show ip ospf interface brief

(A) 1
(B) 5
(C) 2
(D) 0

2 is the correct answer.

The show ip ospf interface brief command lists a pair of counters under the heading ‘Nbrs F/C’. The first of the two numbers represents the number of fully adjacent neighbors (2 full adjacent neighbors in this case), and the second number represents the total number of neighbors.