The first option is unlikely, Apple said no but the UK were probably already speaking to their Five Eyes pals in the US. I don't think they ever expected Apple to relent and it was all just a gambit in the larger picture.

The second option, by far the most likely in my opinion.

The third option, the US doesn't need Apple to cooperate so this also seems unlikely.

Remember, any individual or group of people can be subject to secret gag orders around US intelligence capabilities. Tim Cook can say whatever he says, but you can't believe a word of it as a result.