Another Logic Puzzle

Suppose you have two rooms. In room A are three light switches. In room B are three typical desk lamps. Each light switch in room A turns on/off a different lamp in room B. The light switches can only be pulled to render a light on or off; there is no mid-way dimming function. The rooms are completely separate from and opaque between each other. And finally, there is no geographic correlation between the arrangement of switches in room A and the lamps in room B.

You start off in room A, where all the switches are pointing to off. You can do whatever you want to any of the switches. After you are done, you are allowed to go to room B where you can see the results of whatever you did. You are not allowed to go back to room A and fiddle with more switches after going into room B.

The question for this puzzle is: Which light switch toggles which lamp?

( Answer )