Well, if I understood your intent correctly, and taking into account that you provided very little information about your workflow, this is what I came up with:
- Just add the following script as mouse-up action of the "Yes" radio button
this.getField("myChoices").display = display.hidden;
this.getField("QUESTION2").setFocus();
this.resetForm(["myChoices"]);
- The slide below illustrates how the "Yes" radio button works with this script:

- and add this line to the "No" radio button
this.getField("myChoices").display = display.visible;
this.getField("myChoices").setFocus();
app.alert("Please select one of the options listed in the dropdown menu", 1);
- The slide below illustrates how the "No" radio button works with this script:
