The correct answer is option 'C', which is the "show ip interface" command. This command allows you to determine whether an IP access list is enabled on a particular interface.

The "show ip interface" command provides detailed information about the configuration and status of all interfaces on a router. It displays a summary of each interface, including its IP address, subnet mask, status, and protocol. Additionally, it provides information about any access lists applied to the interface.

Here is a detailed explanation of how the "show ip interface" command works:

1. Accessing the router: First, you need to access the router's command-line interface (CLI) using a console cable or a remote management protocol such as Telnet or SSH.

2. Executing the command: Once you are in the router's CLI, you can enter the "show ip interface" command. This will display a list of all interfaces on the router along with their respective IP addresses, subnet masks, and status.

3. Analyzing the output: Look for the specific interface you are interested in. The command will display a line indicating whether an IP access list is enabled on that interface. If an access list is enabled, it will show the name or number of the access list.

4. Interpretation: If the output shows an access list enabled on the interface, it means that packets passing through that interface will be filtered based on the rules defined in the access list. On the other hand, if no access list is enabled, all packets passing through the interface will be allowed by default.

5. Further analysis: If you want to view the details of the access list, you can use the "show access-lists" command. This command will display the access lists configured on the router, including their rules and actions.

In conclusion, the "show ip interface" command is used to determine whether an IP access list is enabled on a particular interface. It provides valuable information about the configuration and status of all interfaces on the router, including the presence of access lists.