JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.3.0/knockout-min.js"></script>
<select data-bind="options: options, selectedOptions: myObservable">
</select>
<span data-bind="text: ko.toJSON(myObservable())"></span>

JavaScript

$(function() {
    ko.applyBindings(new ViewModel());
});

var ViewModel = function (model) {
    var self = this;
    
    self.myObservable = ko.observableArray();
    self.options = ["123", "345", "456"];
};