Which of these islands is not part of the UK?
Jersey is a self-governing parliamentary democracy under a constitutional monarchy, with its own financial, legal and judicial systems, and the power of self-determination. It is not part of the United Kingdom and has an international identity separate from that of the UK, but the United Kingdom is constitutionally responsible for the defence of Jersey.
Anglesey is in Wales. North Ronaldsay is the northernmost of the islands of Orkney (in Scotland) and Tresco is one of the Isles of Scilly (in England).