When light (or electrical signals) travels in a guided medium 
its speed is ~
  the same as in free space~
  less than in free space~
  greater than in free space
~~
What is the usual cause of queueing delay in packet switched networks?~
  More than one packet is ready to be sent on a link at a given time~
  Links break down and can't be used for awhile~
  Packets have to traverse multiple links to get to their destination~
  Some packets are more important than other packets and go to the head of the line