show fileupload control when dropdown option click

Question

When option is selected from dropdown for eg: 

i have one dropdown in which two listitem " yes & no"

if yes is selected then fileupload control shown otherwise hide

<label for="inputText" class="col-sm-4 col-form-label">Land</label>
                            <div class="col-md-8">
                                <asp:DropDownList ID="ddl" runat="server" Height="16px" Width="132px">

                                    <asp:ListItem Value="01">Yes</asp:ListItem>
                                    <asp:ListItem Value="0">No</asp:ListItem>

          </asp:DropDownList>

            pn.Own_Land = Convert.ToInt32(ddl.SelectedValue);