title: Relation between dropdown structure and proccessing it's data in forms
body: <p>I've known three ways for creating dropdowns which I can use in forms till now:
  1) using HTML "form-dedicated":select and option value=""
  2) using Bootstrap framework: div class="dropdown" Button class="btn btn-secondary dropdown-toggle" and div class="dropdown-menu having a class="dropdown-item"
  3) using HTML UL-list: ul li a href="x" and so on </p>
  
  <p>Could anyone tell me if there are any differences in treating data from this three types of dropdowns by server? Which one I should use to obtain not only good looking but also efficient form ?</p>