Which of the following statements are correct?

I. The User Datagram Protocol $($UDP$)$ is used for applications that requires constant data flow.

II$.$ The header size in Transmission Control Protocol $($TCP$)$ is small when compared to the header size of User Datagram P $($UDP$).$

III. The Transmission Control Protocol $($TCP$)$ is byte oriented.

IV$.$ The User Datagram Protocol $($UDP$)$ is used for routing.

I, II$,$ and IV only