Please Enter Details of what permission you have to stay in this country (question)

Hi, I'm currently filling out my spouse visa on the Visa4UK website to join my husband who is a UK citizen (I am a US citizen). I'm slightly confused about the question: "Please Enter Details of what permission you have to stay in this country" in the "Passport / Travel Document" section. Is it asking what right I have to stay in the US or UK?

Should I put something like "Wife of UK citizen" or "US passport"?