Fix exit plan to send option response type

Exit plan responses should use type 'option' not 'text' since they're
selecting from a predefined set of options.

public/index.html

@@ -778,7 +778,7 @@
           return;
         }
         response = {
-          type: 'text',
+          type: 'option',
           value: selected.value,
         };
       }