How to generate a drop down list of timezone using PHP ?

<?php

function select_Timezone($selected = '') {

    // Create a list of timezone
    $OptionsArray = timezone_identifiers_list();
        $select= '<select name="SelectContacts">
                    <option disabled selected>
                        Please Select Timezone
                    </option>';
        
        while (list ($key, $row) = each ($OptionsArray) ){
            $select .='<option value="'.$key.'"';
            $select .= ($key == $selected ? : '');
            $select .= '>'.$row.'</option>';
        } 
        
        $select.='</select>';
    return $select;
}

echo select_Timezone() . '<br>';

?>

<?php

// Create a timezone identifiers
$timezone_identifiers = 
    DateTimeZone::listIdentifiers(DateTimeZone::ALL);

echo "<select>";

echo "<option disabled selected>
         Please Select Timezone
      </option>";

$n = 425;
for($i = 0; $i < $n; $i++) {
    
    // Print the timezone identifiers
    echo "<option value='" . $timezone_identifiers[$i] . 
        "'>" . $timezone_identifiers[$i] . "</option>";
}

echo "</select>";

?>

<?php

$timezone_identifiers = 
    DateTimeZone::listIdentifiers(DateTimeZone::ALL);

$Africa = range(0, 51);
$America = range(52, 198);
$Asia = range(211, 292);
$tz_stamp = time();

echo "<center><select style='padding:20px;
     font-family: Courier New, Courier, monospace;
     width: 450px;border:2px solid #a09;
     outline: none;'>";

echo "<option style='color:#FFF;font-family:Cambria;
          background-color:#a09;'><h3>Africa</h3>
      </option>";

foreach($Africa as $x) { 
    $tzone[$x] = date_default_timezone_set(
                        $timezone_identifiers[$x]);
    
    echo "<option>" . $timezone_identifiers[$x] .
            ' @ ' . date('P', $tz_stamp);"</option>";
}

echo "<option style='color:#FFF;font-family:Cambria;
        background-color:#a09;font-size:15px;'>
        <h3>America</h3></option>";

foreach($America as $x) { 
    $tzone[$x] = date_default_timezone_set(
                        $timezone_identifiers[$x]);
    
    echo "<option>" . $timezone_identifiers[$x] . 
            ' @ ' . date('P', $tz_stamp);"</option>";
}

echo "<option style='color:#FFF;font-family:Cambria;
        background-color:#a09;font-size:15px;'>
        <h3>Asia</h3></option>";
        
foreach($Asia as $x) { 
    $tzone[$x] = date_default_timezone_set(
                        $timezone_identifiers[$x]);

    echo "<option>" . $timezone_identifiers[$x] .
            ' @ ' . date('P', $tz_stamp);"</option>";
}

echo "</select></center>";
?>