default selected items dynamically in several options in angular

i am seeing the example here https://docs.angularjs.org/api/ng/directive/select and this have 3 select with the same value, how can i have different values selected in my options?

i have this:

    <li ng-repeat="tarea in tareas">
      <input type="checkbox" ng-model="tarea.COMPLETADA" ng-change="updTarea(tarea.ID)"/>
      <span class="done-{{tarea.COMPLETADA}}" >{{tarea.NAME}} {{tarea.CLASIFICADORES}}</span>
      <select ng-model="selectedOpt" 
      ng-options="clasificador.NAME for clasificador in clasificadores">
      </select>
      <button class="buttons delete right" ng-click="delTarea(tarea.ID)"> Eliminar</button>
    </li>

so i can have 5,10,15 options, and i want to make a selected item with the value that i have in tarea.CLASIFICADORES, i tried with this

$scope.selectedOpt = $scope.clasificadores[1]

but that make all the options with the same value, like in the example...

how can i make different selected item in my options dynamically with a value i have in my ng-repeat in every item?

i load the data with ajax...

my problem is to set the default selected item with the tarea.CLASIFICADORES. for example, i have a todo list that have a classifier, i want my ng-options to select by default my database value clasifier when the page is load

The problem is, that you are using the same scope variable for all selections. You could store the selected options in an array too like this:

function TestCtrl($scope) {
  $scope.items = [
    { id: 1, class: 1 },
    { id: 2, class: 2 },
    { id: 3, class: 1 },
  ];
  $scope.classes = [
    { name: "class 1", id: 1},
    { name: "class 2", id: 2},
    { name: "class 3", id: 3}
    ];
  };

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>

<div ng-app>
  <div ng-controller="TestCtrl">
    <div ng-repeat="currentItem in items">
      <select ng-model="selectedClass[$index]" ng-init="selectedClass[$index]=(classes|filter:{id: currentItem.class})[0]" ng-options="class.name for class in classes track by class.id" >
      </select>
      selected class: {{selectedClass[$index]}}
    </div>
  </div>
</div>

In this example I take use of the variable $index, which is set by the ng-repeat directive. As the name suggests it contains the current index of the repeat-loop.

UPDATE

I updated the code-snippet so it sets the default value for each select input.

The different items now contain a field with the id of the corresponding class. I initialize the select input with ng-init. With this directive I set selectedClass[$index] which is the selected value for the current item. As we only have the class-id as a property of the items I use a filter to find the corresponding class object with the id (classes|filter:{id: currentItem.class})[0]

To get rid of the filter you could just set the class of each item to the full class-object instead of the id.