Which is a correct statement about sliding windows used with TCP?

The window size, which is a buffer, is established and agreed upon by the sender and receiver during the three-way handshake. Sliding windows does not allow for data of different lengths to be padded; it is used for fixed-length data segments. Port binding is used by TCP and UDP to indicate which upper-layer protocol (application) created the request. Routers only examine layer 3 information by default, so they can make decisive routing decisions.