how to get the value of the checked row

Please Help me. i need to get the value of the selected option if the checkbox is checked. For Example. i Checked the checkbox in the 3rd row. in another page. i want to get the value of the 3rd row selected option. im kinda new to this and hoping for you guys to help me. please dont use the $a to get the data. is there another way? ... Thank you guys.

<table>
    <?php
        for($a = 0;$a <=3; $a++){
            echo '<tr><td>';
            echo '<input type = "checkbox">';
            echo '</td><td>';
            echo '<select>';
            echo '<option>';
            echo  $a;
            echo '</option>';
            echo '</select>';
            echo '</td></tr>';
        }
    ?>
</table>