mfwebdesigner

Use this function

function my_wpcf7_form_elements($html) {
    //wp_send_json($html );
    $text = 'your text here';
    $html = str_replace('Please choose an option',  $text, $html);

    return $html;
}
add_filter('wpcf7_form_elements', 'my_wpcf7_form_elements');