Refer to the exhibit. 
If CDP is enabled on all devices and interfaces, which devices will appear in the output of a show
cdp neighbors command issued from R2?
A.
R2 and R3
B.
R1 and R3
C.
R3 and S2
D.
R1, S1, S2, and R3
E.
R1, S1, S2, R3, and S3
Explanation: