The original question was about weather minima at destination, not alternate, so the minima required are the actual minima on the approach plate.
The determining factor will be approach specific. For a catIII ILS it will be RVR, but as you go down the approaches, it will become more muddled.
For example, at my home base, ILS approach minima require a 200' cloudbase, but 800m vis, due to an offset approach. To circle, you need 2400m and 500' cloudbase.
At the interview, did they show an approach plate to see if you could work it out? If not, I would suggest it is an impossible question to answer without more information.
HTH