Object not found when clicking hyperlink

Hello, I'm learning IC and I came across the following problem. When I click on a link in a home test, I would like to be transferred to another page and use another controller, but when clicking, I get this error:

Objeto não encontrado!

A URL requisitada não foi encontrada neste servidor. 
O link na página referida parece estar com algum erro ou desatualizado. .
Por favor informe o autor desta página sobre o erro.

This is my Home.php

class Home extends CI_Controller {

    function __construct(){
        parent::__construct();
    }

    public function index(){
        $this->load->view('pages/home/index');
    }
}

And this is my views / pages / home / index.php o:

<a href = "<?php echo site_url('application/controllers/ong'); ?>" class="btn btn-link">Ong</a>

htaccess:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php [L]