How does the router$-$on$-$a$-$stick model for inter$-$VLAN routing differ from traditional routing? Select one: a$.$ The router$-$on$-$a$-$stick model uses a single physical interface on the router with only the no shutdown command issued. b$.$ The router$-$on$-$a$-$stick model uses subinterfaces on the switch with only the no shutdown command issued on the physical interface. c$.$ The router$-$on$-$a$-$stick model uses subinterfaces on the router with only the no shutdown command issued on the physical interface. d$.$ The router$-$on$-$a$-$stick model uses multiple physical interfaces on the router, each configured with a different Layer $3$ address.