JSFiddle - React, Tailwind, and code Playground

HTML

<select id="first-choice">
   <option value="English">English</option>
   <option value="Spanish">Spanish</option>
</select>

<select id="second-choice">
   <option value="Spanish">Spanish</option>
   <option value="English">English</option>
</select>

JavaScript

$("#first-choice").change(function() {
    var userSelected = $(this).val();
    var otherOption =  $('#second-choice option[value!="' + userSelected + '"]').get(0);
    $('#second-choice').get(0).selectedIndex = otherOption.index;
});