Exercise:

Add the required classes and attributes to create a dropdown list.

<div class="
w3exercise_input_no_0
">
  <button type="button" class="btn btn-primary 
w3exercise_input_no_1
" 
w3exercise_input_no_2
>
    Dropdown button
  </button>
  <ul class="
w3exercise_input_no_3
">
    <li><a class="
w3exercise_input_no_4
" href="#">Link 1</a></li>
    <li><a class="
w3exercise_input_no_5
" href="#">Link 2</a></li>
    <li><a class="
w3exercise_input_no_6
" href="#">Link 3</a></li>
  </ul>
</div>