<label for="organizerMultiple">Multiple</label><select class="form-select js-choice" id="organizerMultiple" multiple="multiple" size="1" name="organizerMultiple" data-options='{"removeItemButton":true,"placeholder":true}'>
  <option value="">Select organizer...</option>
  <option>Massachusetts Institute of Technology</option>
  <option>University of Chicago</option>
  <option>GSAS Open Labs At Harvard</option>
  <option>California Institute of Technology</option>
</select>

<label for="organizerSingle">Single</label><select class="form-select js-choice" id="organizerSingle" size="1" name="organizerSingle" data-options='{"removeItemButton":true,"placeholder":true}'>
  <option value="">Select organizer...</option>
  <option>Massachusetts Institute of Technology</option>
  <option>University of Chicago</option>
  <option>GSAS Open Labs At Harvard</option>
  <option>California Institute of Technology </option>
</select>