Change A Subform Based On A Value In Mainform

I have a main form with a control that can take one of three values. And I would like to add a subform that work as follows.

Selecting each value should change what the subform displays like this.
Control Subform
A Select * from TableA where Key = "A"
B Select * from TableB where Key = "B"
C Disable subform somehow because it doesn't apply

Could someone please provide some advice on how I could do this.

Thanks

Fearless