How to update Choice column in SharePoint

Question

I need update choice column. Let say my column has values like "A", "B". Now I need to insert their a new value like "C". My following code is not working.

using (SPSite site = new SPSite(siteUrl))
                {
                    using (SPWeb web = site.OpenWeb())
                    {
                        web.AllowUnsafeUpdates = true;
                        var spList = web.Lists[listName];
                        SPFieldChoice spChoiceField = (SPFieldChoice)spList.Fields[fieldName];
                        spChoiceField.Choices.Add(value);
                        spChoiceField.Update();
                        spList.Update();
                        web.AllowUnsafeUpdates = false;
                        return "Field has been updated with new value: " + value;
                    }
                }

Answer 1

spChoiceField.Choices.Add(value);

Solved by changing above line by following

spChoiceField.AddChoice(value);