We have the queuing theory which gives us the in depth knowledge of queuing systems which helps us to predict the queue length and the waiting time at the respective nodes in an network. A group of queuing systems together constitute the queuing network. The queuing theory helps to cope with the demand of various services in an queuing network composed of queuing systems.
D. The chocolate cake will be served to the queen. This is the only one not in past tense. Active means present or near present, hence the word "will."
