Dropdown default value

[eluser]Ninja[/eluser]
Controller

Code:

$client = new Client();
            $client->get('id');
    
            foreach($client->all as $entry)
            {
                $clientID = $entry->id;
                $entry->company->get('companyname');
                $companyName = $entry->company->companyname;
                $data['parent'][$clientID] = $companyName;    
            }

View

Code:

<?php echo form_dropdown('Parent', $parent )?>

Im trying to set the default value for the dropdown to something like "Not Applicable"
With an index of 0. This dropdown is for Parent clients (ie. The client of a client) but not all clients will have a parent client.