A. 192.168.2.0/24
For an IPsec VPN between site A and site B, the administrator has configured the local quick mode selector for site A as 192.168.1.0/24 and the remote quick mode selector as 192.168.2.0/24. This means that the VPN will allow traffic to and from the 192.168.1.0/24 subnet at site A to reach the 192.168.2.0/24 subnet at site B.
To complete the configuration, the administrator must configure the local quick mode selector for site B. To do this, the administrator must use the same subnet as the remote quick mode selector for site A, which is 192.168.2.0/24. This will allow traffic to and from the 192.168.2.0/24 subnet at site B to reach the 192.168.1.0/24 subnet at site A.
Therefore, the administrator must configure the local quick mode selector for site B as 192.168.2.0/24.