Display choice when out of stock

If you want to keep the Choice displayed, even when it is out of stock, but make it unselectable, you need to do the following:

Press edit on the option

Scroll down to the list of choices. Press edit on the choice:

Scroll to the Inventory section, and select checkbox "Show when out of stock" and Save Choice -> Save option -> Save product

Here is what it will look like, this choice is unclickable: