在MVC3中设置所选选项

public class MyModel
{
    public string SelectedOption { get; set; }
    public List<SelectListItem> AvailableOptions { get; set; }
}

public ActionResult Index()
{
    var model = new MyModel();
    model.AvailableOptions = new List<SelectListItem>
    {
        new SelectListItem { Text = "Option 1", Value = "1" },
        new SelectListItem { Text = "Option 2", Value = "2" },
        new SelectListItem { Text = "Option 3", Value = "3" }
    };
    return View(model);
}

@model MyModel

@using (Html.BeginForm())
{
    @Html.DropDownListFor(m => m.SelectedOption, Model.AvailableOptions, "Select an option")
   <input type="submit" value="Submit" />
}

[HttpPost]
public ActionResult Index(MyModel model)
{
    // 处理所选选项，例如将其保存到数据库
    // ...

    return RedirectToAction("Index");
}