Ross is running a small data entry back office, for which he has contracted you for network management. Ross has made it very clear that because he has just started the company, he wants to cut down on expenses wherever he can. One such option involves the router. He wants to exchange the router with a similar but less expensive alternative. Which one of the following will you refer to Ross in such a situation?

a$.$

A root port

b$.$

An SDN $($Software$-$Defined Networking$)$ controller

c$.$

A Layer $3$ switch

d$.$

Storm control