When sending a packet of data from source host to a destination host over a fixed route. which of the delay components are variable?
propagation delay
transmission delay
processing delay
queuing delay
none of the above

Queuing delay

Explanation:Queuing delay is the variable delay that occurs while the packet transmission is assigned in the queue.The time at which insertion of the packet in queue takes place and the time that it has reached the address creates the difference which is known as the queuing delay.

The factors that cause this delay are available link numbers in the queue, time of arrival, process of arrival etc.Other options are incorrect because they don't have the variable component at the time of the data packet transmission .Thus the correct option is queuing delay.