Secure lobby switchport gi1/0/15 and limit allowed MAC addresses to two. Which configuration fulfills this requirement?

The correct configuration enables port security on the interface and then sets the maximum number of allowed MAC addresses to two. The switchport port-security command globally enables port security on the interface, and switchport port-security maximum 2 specifies the limit. The other options are incorrect because they either attempt to specify a static MAC address (which isn't requested and doesn't limit the count) or use incorrect syntax. Specifically, switchport port-security mac-address is used to statically define allowed MAC addresses, not to set a limit, and the last option combines incorrect commands and syntax.