Which of the following choices would be best for communicating a complex policy change to…

Which of the following choices would be best for communicating a complex policy change to employees in a company with offices all over the world?

 a. A teleconference followed by an email message

b. Instant messaging (IM)

c. A traditional typed memo sent via regular postal mail

d. A posting on an internal website with an email message alerting employees to the change and directing them to the website for more information