<div class="input-group mb-4">
   <div class="input-group-prepend">
      <label class="input-group-text" for="inputGroupSelect01">Options</label>
   </div>
   <select class="custom-select" id="inputGroupSelect01">
      <option selected>Choose...</option>
      <option value="1">One</option>
      <option value="2">Two</option>
      <option value="3">Three</option>
   </select>
</div>