What is a Firewall? (Choose the best answer)

A.
A system designed to allow influx of externalusers access to or from an internal network

B.
A system designed to connect to the internets and control communications between separate servers

C.
A system designed to allow unauthorized access to or from an internal network

D.
A system designed to connect to the intranets and control communications between separate servers

E.
A system designed to prevent unauthorized access to or from an internal network