$startTime = 01:00:00;
$endTime = 07:00:00;

<select class="" name="time">

  <?php while($endTime != $startTime){

    $s = $startTime;
    $e = date("H:i:s", strtotime("$startTime + 1 hours"));
  ?>
  <option value="1"><?php echo date('g:i a', strtotime($s)); ?> - <?php echo date('g:i a', strtotime($e)); ?></option>

  <?php $startTime = $e;

  }?>

</select>