$1.[20$ Points, $5$ pts each$]$ True $($T$)$ or false $($F$)$: a$.$ Encoding, framing, reliable delivery, and shared medium access control are services provided by the application layer protocols. b$.$ Transmission delay depends on the length of communication medium and speed of propagation over that medium. c$.$ By encapsulation, each layer adds a header containing control information to information received from the layer above it$.$ d$.$ In the TCP$/$IP protocol suite, a protocol at layer i depends on the services provided by protocols at both layers i$-1$ and i$+1.$