Refer to the exhibit. The router of the company failed and was replaced. After the replacement, hosts C and D in the Education office are able to ping each other, but they are unable to access the hosts in the Accounts office. What is the likely cause of the problem?

The IP address at the fa0/0 interface of the router is incorrectly configured.
The subnet mask at the fa0/1 interface of the router is incorrectly entered. 

The IP address at the serial interface of the router is incorrectly configured.
The hosts in the Accounts office are not on the same subnet as the hosts in the Education office.