What is the purpose of the switchport command?

What is the purpose of the switchport command?

Switch(config-if)# switchport port-security maximum 1

Switch(config-if)# switchport port-security mac-address 0018.DE8B.4BF8
A . It ensures that only the device with the MAC address 0018.DE8
B . 4BF8 will be able to connect to the port that is being configured.
C . It informs the switch that traffic destined for MAC address 0018.DE8
D . 4BF8 should only be sent to the port that is being configured.
E . It will act like an access list and the port will filter packets that have a source or destination MAC of 0018.DE8
F . 4BF8.
G . The switch will shut down the port of any traffic with source MAC address of 0018.DE8
H . 4BF8.

Answer: A