Hi @scientist ,
This is similar to what I just replied.
In your case, it is triggered when you click the list of answer, or just buttons that have actions if you are not using list.
Make custom list visible for countdown inside it to do unchecking and then you can check the selected answer.
Adalo is quite strong in logic, but the way that it presents it to us making it tough to see the whole logic at once.
UI of logic in no code should be treated differently than UI for visual elements, but that could be a factor that Adalo want to avoid as it can be marked as low code.