How to call different read functions from web API to windows forms application?

I have a windows forms application that when a form loads, the web API retrieves data and sends it to the form. I have 2 GET functions in the API but I don't know how to call the 2nd one. Only the 1st one is called.
Below is the code of the click event and the API code.

So what should I do in the windows forms function to tell the program that I want to use the other function instead of the first?

Windows forms code:

private void ACombo_KeyDown(object sender, KeyEventArgs e)
        {
                LoadCombo();
        }

private async void LoadCombo() //populate combobox onLoad
        {

            using (var client = new HttpClient())
            {

                using (var response = await client.GetAsync(URI))
                {
                    if (response.IsSuccessStatusCode)
                    {
                        var productJsonString = await response.Content.ReadAsStringAsync();
                        ACombo.BeginUpdate();

                        table = JsonConvert.DeserializeObject<DataTable>(productJsonString);
                        for (int i = 0; i < table.Rows.Count; i++)
                        {
                            ACombo.Items.Add(table.Rows[i].ItemArray[0]);
                        }
                        ACombo.EndUpdate();

                    }
                }
            }
        }

And here's the API functions(Both in one controller):

public DataTable getX()
        {
            DataTable table = new DataTable();
            string query = "SELECT <anything> FROM X"; //just as an example
            table= DAL.dynamiccommection(query, "contsh_conmam");
            return table;
        }

//2nd function

public DataTable getY()
        {
            DataTable table = new DataTable();
            string query = "SELECT <anything> FROM Y"; //just as an example
            table= DAL.dynamiccommection(query, "contsh_conmam");
            return table;
        }