This will get you the choices array inside $field
variable:
$choices = $field[ 'choices' ];
From there, you can iterate with either a while or foreach loop depending on what you are trying to do with the array.
EDIT: rereading your question, you specify what you are trying to do! Sorry for skipping that part!
echo '<ul>';
foreach($choices as $key => $choice):
echo '<li>' . $key . ' and ' . $choice . '</li>';
endforeach;
echo '</ul>';
Should produce:
- orange_county and Orange County
- los-angeles and Los Angeles
This should not be considered complete code. Escape your output for security’s sake. Just illustrating a concept here.