I have a dropdown list and when when user selects a value and a different forms will appear depends on what the selected value. My file is in html. I'm using bootstrap for my design.
here is my sample code:
<form name="exmType" method = "POST">
<select class="form-control" name="txtType" class="select" method = "post"
onChange="this.form.submit();" style="width:300px;">
    <option value="">Option A</option>
    <option value="1">Option B</option>
    <option value="2">Option C </option>    
<?php
if (isset($_POST['txtType'])) {
if ( $_POST['txtType'] == "" ){
       *display form a*
} elseif ( $_POST['txtType'] == 1 ){
        *display form b*
 } elseif ( $_POST['txtType'] == 2 ){
        *display form c*
 }
}
?>
  </select>
</form>
 
     
     
     
    