^^^ I was trusting the 'C' at the start. ('Chalki' is the only island which fits). However a quick look at a map suggests that 'Rhodes' is, indeed, the correct answer. Sorry!
I'm wondering if the setter was confused by some travel firms who offer holidays to both 'Rhodes' and to 'The Dodecanese Islands', when they should really refer to 'The Other Dodecanese Islands'?