Your document contains a dropdown formfield, not a dropdown content control. You could use three IF tests to insert whichever of the three tables you want. However, those tables could not contain formfields of their own and none of the content would be editable. Consequently, any solution to your problem would require some programming and for the code to be either:
a) stored in the document's template; or
b) stored in the document itself.
The approach to be taken depends on what you plan to do with the document.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]