School game

My high school computer lab has an almost annual game like jeopardy, but with questions about computers. We currently have it set up with four differently colored light bulbs that each work from a little switch, it's pretty nice. What we really want is to hook it up in a way that only one light can turn on at a time. I have no idea how to do this, but i would assume we would need to wire each light seperately to a main hub. If anyone could give me help with this, it would be much appreciated.

I know I have a better circuit than this one - maybe someone else has one.

**broken link removed**

Here it is...
https://www.e-insite.net/ednmag/contents/images/50301di.pdf

First Event Detector

Try this ...
https://www.e-insite.net/ednmag/index.asp?layout=article&articleid=CA223207#ref