When ten e-mail messages are sent successively from Company A to Company B, they
may arrive at Company B in a different order from the order they are sent. Which of
the following is the most possible reason for this phenomenon?
a) There is a problem with the setup of Company A’s mail server.
b) There is a problem with the setup of Company B’s firewall for e-mail.
c) There is a possibility that e-mail delivered late is falsified on the way.
d) There is a possibility that each e-mail is sent via different transfer routes.