To generate a dropdownlist control in MVC using HTML helpers, you can use the DropDownListFor method provided by the HtmlHelper class. Here's an example of how you can use it:

Let's assume you have a model called MyModel with a property named SelectedOption that will hold the selected value from the dropdownlist. You also have a list of options called OptionsList that will populate the dropdownlist.

First, make sure you have the necessary namespaces imported at the top of your Razor view file:

@using System.Collections.Generic
@using System.Web.Mvc

Then, in your Razor view file, you can generate the dropdownlist control like this:

@model MyModel

@using (Html.BeginForm("ActionName", "ControllerName", FormMethod.Post))
{
    @Html.DropDownListFor(model => model.SelectedOption, new SelectList(Model.OptionsList), "Select an option")
    <input type="submit" value="Submit" />
}

In this example, model => model.SelectedOption specifies the property in your model that will hold the selected value from the dropdownlist.

new SelectList(Model.OptionsList) creates a new SelectList object using the OptionsList property from your model. This list will populate the dropdownlist options.

"Select an option" is an optional parameter that sets the default option in the dropdownlist. You can replace it with any other text you prefer.

The Html.BeginForm method creates a form element around the dropdownlist, and the input element with type="submit" creates a submit button.

Make sure to replace "ActionName" and "ControllerName" with the appropriate values for your MVC application.

When the form is submitted, the selected value from the dropdownlist will be passed back to the specified action method in the specified controller, which you can handle accordingly.