Which or the following are the Uuce major components of a queuing system?

a$.$ The source population, how customers exit the system and the queuirg discipline.

c$.$ The sourco population. how the custames exis the system, and the serving system.

d$.$ The source population and the way customers arrive at the system, the serving systems, and how customers exit the system

e$.$ The numhet of servers the service spedi, and the waiting lifse