How to output json in Select options?

Question

JSON

I am making an ajax request. Passing an array with php "echo json_encode($data);" in js. How can I take the data from this array and output it to options?
I do so

success: function (data) {
                        $.each(data, function(key, val){
                            $('.select-secession').append('<option value="' + val + '">' + val + '</option>');
                        });
                    },

but it only outputs the first option, what's wrong?