This is the JavaScript onChange event that will take the user to the URL in the option value.
<select id="branchselect" class="form-control" id="sel1" onChange="if(this.options[this.selectedIndex].value != '-1'){window.document.location.href=this.options[this.selectedIndex].value;}">
<option value="-1" selected>Select Branch:</option>
<option value="1">Option 1</option>
<option value="2">Option 2</option>
<option value="3">Option 3</option>
<option value="4">Option 4</option>
</select>