<div class="dropdown">
<button class="btn btn-primary dropdown-toggle" type="button" data-toggle="dropdown">branches <span class="caret"></span> </button>
<ul class="dropdown-menu">
<li><a href="#">CSE</a> </li>
<li><a href="#">Mech</a> </li>
<li><a href="#">IT</a> </li>
<li><a href="#">Civil</a> </li>
</ul>
</div>