what IOS command?

The partial output displayed in the exhibit is a result of what IOS command? (Click on the Exhibit(s) button.)

A.
switch# show running-config

B.
switch# show standby vlan1 active brief

C.
switch# show hsrp 1

D.
switch# show standby

Explanation:
The command shows standby produces the output displayed in the exhibit. This command displays information about HSRP on all configured interfaces and for all
HSRP groups. Important information in the exhibit includes that this router is the active router, the virtual IP address for the HSRP group is 172.16.1.20, the address
of the standby router is 172.16.1.6, and the router is configured to preempt.
The command show running-config will display the complete configuration of the device, including the configuration of HSRP, but will not display the current status
of HSRP on the switch.
The command show standby vlan 1 active brief provides a summary display of all HSRP groups on the switch that are in the active state. This output would provide
basic information, not nearly the detail indicated in the exhibit. The following is an example of output for show standby vlan 1 active brief:
Interface Grp Prio P State Active addr Standby addr Group addr
Vlan1 0 120 Active 172.16.1.5 Unknown 172.16.1.20

The command show hsrp 1 is not valid due to incorrect syntax.
Objective:
Infrastructure Services
Sub-Objective:
Configure, verify, and troubleshoot basic HSRP

Cisco > Cisco IOS IP Application Services Command Reference > show ip sockets through standby name > show standby
Cisco > Cisco IOS IP Application Services Configuration Guide, Release 12.4 > Part 1: First Hop Redundancy Protocols > Configuring HSRP