Specific Actions From Random Instances

Hello,

I have 3 different enemies and 3 different groups of gun turrets. I want to randomly destroy one turret from any group whenever any enemy reaches the target. Depending on which turret is destroyed I would like to have a single instance of that turret destroyed. What I'm having trouble with is setting it up so that any enemy reaching the target randomly selects any 1 turret from any of the 3 groups of turrets and destroys an instance of that turret. I'm comfortable setting up "or" blocks but can't figure out how to destroy the appropriate turret depending on which one was randomly selected.

Any ideas?

try putting all the turrets in another object group then randomly selecting a turret from their