Hey. Honestly, in my opinion, the career doesn’t even need to be remotely close to law. Seems the law firm just wants to see your personality in this. Though, if I were to answer the question, I would personally choose a career which links to law on an international scale - their clients, for example. The reason I would do this is largely because of my career journey - I had initially wanted to become an investment banker. This will differ between everyone, so choose something you are comfortable with explaining in sufficient detail and with specificity. On your last paragraph, I believe any field has those qualities so you could really touch on anything.
I have quoted a post I made in the past above for more detail.