A. The presentation layer which is layer number 6, is responsible for independence from differences in representation.
B. The Application layer handles protocols such as HTTP, FTP and SMTP.
C. The network layer is responsible for routing, and algorithms such as bellman ford are used in routing to find the shortest path.
D. The Transport layer deals with reliable end to end process. it deals with transfer of data between end users and also the reliable transfer of services to upper layers.
E. The Physical layer handles the transmission interface between devices and transmission medium.