When select option All request it change to Pending Request after display data why it clear after display data?

Question

I work on asp.net MVC I face issue selected value All requests cleared after display result data and back to Pending Request automatically .

so my issue on selected value option if I select option All requests it display all requests success but drop down selected option change to Pending Request .

so How to solve issue selected option clear after display data

action GetSelectedDropDownChanged on controller WorkforceRequests hit and catched when make debug and detect value 1 if i select pending request and 2 if i select all request

but issue when select option All request it back to option Pending Request why and so How to prevent this behavior from happen

code details

<form action="/WorkforceRequests/GetSelectedDropDownChanged"  method="post">
            <select class="form-control" id="statusselect" name="statusselect">
                <option value="1">Pending Request</option>
                <option value="2">All requests </option>
            </select>
        </form>

on controller WorkforceRequestsController


        public async Task<ActionResult> GetSelectedDropDownChanged() //Assuming key in your dropdown is string
        {
            string selectedValue = Request.Form["statusselect"].ToString();
            List<WorkforceRequest> workforceRequest = new List<WorkforceRequest>();
            if (selectedValue == "1")
            {


          workforceRequest = Workforce.GetPendingOnPalnningSection(RoleKey.PLS);


            }
            else

                workforceRequest = Workforce.GetAllRequestsOnPalnningSection(RoleKey.PLS);

            return View(workforceRequest);

        }