Angular: pass JSON parameter to controller to filter

How do I pass this parameter to the MVC controller? I am making a dropdown list of my object and department where if I select this object the department below it will be shown in the next dropdown to filter my data.

Here's my angular in sight

        scope.getEntity = http.get('GetEntity').success(function (entity) {
            scope.entities = entity;
        });

        scope.selectEntity = function () {
            var e = document.getElementById("entityList");
            var entity = e.options[e.selectedIndex].value;
            console.log(entity);
        };
        scope.getDepartment = http.get('GetDepartment').success(function (dept) {
            scope.depts = dept;
        });

      

        
        
        
      

    

here's my model where i am getting data from my db.

 public static List<string[]> LoadEntities()
    {
        string sScript = "SELECT [EntityID],[EntityName] FROM [NOP_PR].[dbo].[Entities] where LocationID=39 or LocationID=21";
        List<string[]> results = new List<string[]>();
        using (SqlConnection con = new SqlConnection(m_sConnectionString))
        {
            con.Open();
            using (SqlCommand command = new SqlCommand(sScript, con))
            {
                SqlDataReader reader = command.ExecuteReader();
                while (reader.Read())
                {
                    string[] r = new string[] { reader.GetInt64(0).ToString(), reader.GetString(1) };
                    results.Add(r);
                }
            }
        }
        return results;
    }
    public static List<string[]> LoadDepartment(string EntityID)
    {
        string sScript = "SELECT [DepartmentID],[DepartmentName] FROM [NOP_PR].[dbo].[Departments]"
                             + " WHERE EntityID=" + EntityID + ";";
        List<string[]> results = new List<string[]>();
        using (SqlConnection con = new SqlConnection(m_sConnectionString))
        {
            con.Open();
            using (SqlCommand command = new SqlCommand(sScript, con))
            {
                SqlDataReader reader = command.ExecuteReader();
                while (reader.Read())
                {
                    string[] r = new string[] { 
                        reader.GetInt64(0).ToString(), 
                        reader.GetString(1) };
                    results.Add(r);

                }
            }
        }
        return results;
    }

      

        
        
        
      

    

Here's my controller

 public JsonResult GetDepartment(string EntityID)
    {
        return Json(NomsConnection.LoadDepartment(EntityID), JsonRequestBehavior.AllowGet);
    }


    public JsonResult GetEntity()
    {
        return Json(NomsConnection.LoadEntities(), JsonRequestBehavior.AllowGet);
    }

      

        
        
        
      

    

And my mind

<div class="col-xs-4">
                    <div class="col-xs-10">
                        <h4><b>Search :</b></h4>
                        <div class="input-group">
                            <span class="input-group-addon">
                                <span class="glyphicon glyphicon-search"></span>
                            </span>
                            <input type="text" name="search" data-ng-model="filter" class="form-control" placeholder="Search here (e.g. 151234 or Pille)" />
                        </div>
                        <br />

                    </div>

                    <div class="btn-group" role="group">
                        <button data-ng-click="exportData()" class="btn btn-warning"><i class="glyphicon glyphicon-export"></i>Export to Excel </button>
                    </div>
                </div>



            </div>

      

        
        
        
      

    

Hope someone can help!