Blokk showed you how, if you had a Modal Dialog VI that would ask you "Which option do you want?" and would wait for you to answer the question, you could use to choose which option to do. So now it boils down to writing the Modal Dialog VI.
Write an ordinary VI that lets you choose one of three options. You can use a Radio Button box, or three booleans (with a Text label saying "Please choose one of the following". You can decide "When I make a choice, then I'm done and can exit" (you can use an Event Structure to do this) or you can have a pair of buttons, called "Accept Choice" and "Cancel Choice", that the user is required to push. You design how you want to handle this, and make it happen.
Now, before saving this sub-VI, right-click its icon and open its Properties. Go to the Window Appearance, and choose Dialog. Now push Customize, but only look, don't change anything. Notice some interesting properties have been set -- the VI will "Show its Front Panel when called" (so you can see and interact with its controls) and will "Close afterwards if originally closed" (so it "goes away" when you are done). Notice the Window Behavior is Modal, which means it "sits on top" of other windows and holds things up until it finishes.
If you want, you can go into the Window Run-Time Position and change the Position to Centered (so it pops up right in the middle of the screen, instead of "Where you last saved it".
You now have a Modal Dialog Box that will pop up, allow you to make a (very flexible, you-program-it, choice), and will disappear when you've made your choice.
Bob Schor
