Which of the following code will you use if Defining a root route?

A)  App.Route = Backbone.Router.extend({ route: { '': 'index' }, index: function(){ $(document.body).append("root index route"); } });
B)  App.Router = Backbone.Router.extend({ routes: { '': 'index' }, index: function(){ $(document.body).append("root index route"); } });
C)  App.Router = Backbone.Route.extend({ route: { '': 'index' }, index: function(){ $(document.body).append("root index route"); } });
D)  All of the above

Correct Answer :   App.Router = Backbone.Router.extend({ routes: { '': 'index' }, index: function(){ $(document.body).append("root index route"); } });