The network administrator has found the following problem. 
The remote networks 172.16.10.0, 172.16.20.0, and 172.16.30.0 are accessed through the
Central router’s serial 0/0 interface. No users are able to access 172.16.20.0. After reviewing the
command output shown in the graphic, what is the most likely cause of the problem?
A.
no gateway of last resort on Central
B.
Central router’s not receiving 172.16.20.0 update
C.
incorrect static route for 172.16.20.0
D.
172.16.20.0 not located in Central’s routing table
Explanation: