<div class="mt-5">  
  <div class="container-fluid row">
    <div class="row">
      <div class="form-group col-6">
        <label for="exampleFormControlSelect1">Normal select</label>
        <select class="form-control" id="exampleFormControlSelect1">
          <option>1</option>
          <option>2</option>
          <option>3</option>
          <option>4</option>
          <option>5</option>
        </select>
      </div>
      <div class="form-group col-6">
        <label for="exampleFormControlSelect1">Select-bootstrap</label>
        <select class="form-control selectpicker" id="exampleFormControlSelect1">
          <option>1</option>
          <option>2</option>
          <option>3</option>
          <option>4</option>
          <option>5</option>
        </select>
      </div>
    </div>
    <select class="selectpicker" multiple>
      <option>Mustard</option>
      <option>Ketchup</option>
      <option>Relish</option>
    </select>
</div>