You have a few options for this:
(1) Using what you already know about PowerPoint (or could learn very
easily), set up your answers as buttons. The buttons could either be
hyperlinked to slides that say "Right Answer" or "Wrong Answer" or could
use animation triggers to trigger a text box to come in that says "Right
Answer" or "Wrong Answer."
(2) You could use VBA scripting, which is more difficult but will allow
you to do exactly what you want and more (such as keeping score). Check
out the examples at:
http://www.PowerfulPowerPoint.com/
Click on "Examples by Chapter" and start with the examples in Chapter 7.
--David
--
David M. Marcovitz
Microsoft PowerPoint MVP
Director of Graduate Programs in Educational Technology
Loyola College in Maryland
Author of _Powerful PowerPoint for Educators_
http://www.PowerfulPowerPoint.com/