Popular second select after selecting the first select [closed]

Good evening!

I want to populate the second select with the data depending on the first select, I have the following code

View

$(document).ready(function(){
   $("#relatorio").change(function(){
      $.ajax({
         type: "POST",
         url: "carregaDados",
         data: {relatorio: $("#relatorio").val()},
         dataType: "json",
         success: function(json){
            console.log(json);
            var options = "";
            $.each(json, function(key, value){
               options += '<option value="' + key + '">' + value + '</option>';
            });
            $("#filtro").html(options);
         }
      });
   });
});

<div class="form-group">
                                            <label class="col-md-3 control-label">Relatório</label>
                                            <div class="col-md-9">                                                                                            
                                                <select class="form-control" name="relatorio" id="relatorio">
                                                    <option value="0">Escolha um relatório</option>
                                                    <option value="chamadosCliente">Chamados por cliente</option>
                                                    <option value="chamadosTecnico">Chamados por Tecnico</option>
                                                </select>
                                            </div>
                                        </div>

                                       <div class="form-group">
                                            <label class="col-md-3 control-label" for="filtro">Filtro</label>
                                            <div class="col-md-9">                                                                                            
                                                <select class="form-control" name="filtro" id="filtro">

                                                </select>
                                            </div>
                                        </div>

Controller

public function carregaDados(){

        $this->load->model('clientes_model');
        $clientes = $this->clientes_model->buscaNomeCliente();
        echo json_encode($clientes);
}

Model

public function buscaNomeCliente(){
        $this->db->select('id, razaoSocial');
        $query = $this->db->get('clientes');
        return $query->result();
    }

But when it returns the pro ajax data in the View, it returns:

Array [ Object, Object ]

Do not return the data as it has to be, can anyone help me?

Thank you!