Hi cmp,

Use Data tranfer rule to clear control.

For more refer link "Clear Radio button List".  This post is to clear radio button list control, but rules to clear Choice control will also be same as this.

Thanks for your answers.

Instead of choosing the Radio Button List as the display type of the choice control, I altered to Check Box List.

Then, I inserted some rules:

- rule Transfer Data - value of the Choice Control to a Hidden Data Label;

- an advanced condition. If the Hidden Data Label is empty and the Choice Control is not empty then:

- show a message to the user (stating there's an errror)

- stop rule execution.

With this I can deselect the answers that were marked (if there's some mistake when the form is being filled).

There's also possible to validate that there's only one answer marked.