Maintain Selected Value of HTML DropDownList across PostBack in ASP.Net

This way

<select id="ddlCategory" name="ddlCategory1" style="width: 150px">
   <option value="Leave" <%=Request.Form["ddlCategory1"] == "Leave" ? "selected='selected'" : ""%>>Leave</option>
   <option value="Premisssion" <%=Request.Form["ddlCategory1"] == "Premisssion" ? "selected='selected'" : ""%>>Premisssion</option>
   <option value="Com OFF" <%=Request.Form["ddlCategory1"] == "Com OFF" ? "selected='selected'" : ""%>>Com OFF</option>
</select>
<br />
<asp:Button Text="submit" runat="server" />