JSFiddle - React, Tailwind, and code Playground

HTML

<div class="abc">
  <div class="xyz">
    <select name="pqr" class="selectDropdown">
      <option value='1'>1</option>
      <option value='2'>2</option>
      <option value='3'>3</option>
      <option value='4'>4</option>
    </select>
  </div>
</div>

JavaScript

$('.selectDropdown').on('change', function(e) {
    $('select[name="pqr"]').children('option:not(:selected)').prop('disabled', true);
});