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?

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

Answer: C

Explanation:

A Cisco device enabled with CDP sends out periodic interface updates to a multicast address in order to make itself known to neighbors. Since it is a layer two protocol, these packets are not routed. So the devices detected would be immediate connected neighbors.