TCP/IP （ ）layer protocols provide services to the application（ ）running on a computer. The application layer does not define the application itself, but rather it defines（ ）that applications need--like the ability to transfer a file in the case of HTTP. In short, the application layer provides an（ ）between software running on a computer and the network itself. The TCP/IP application layer includes a relatively large number of protocols, with HTTP being only one of those. The TCP/IP（请作答此空）layer consists of two main protocol options--the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).
A.application
B.session
C.physical
D.transport