How do I set the selected item in a drop down box | PHP

<!-- Record set Code -->

<?php

if (isset($_POST['submitSearch'])) {

    include_once 'includes/dbh.inc.php'; // Database Connection

    $searchh = mysqli_real_escape_string($conn, $_POST['searchh']);

    $sqlFormSearch = "SELECT * FROM exchange_order WHERE cus_ac_code = '$searchh';";

    $resultt = mysqli_query($conn, $sqlFormSearch);

    $rowCus = mysqli_fetch_assoc($resultt);

    $queryResultt = mysqli_num_rows($resultt);

}

?>

<!-- Search box -->

<div class="search-box pull-left">

<form action="<?=$_SERVER['PHP_SELF']?>" method="POST">

<input type="text" name="searchh" placeholder="Search..." required>                                

<button type="submit" name="submitSearch" style="margin-left:0.5rem;" class="btn btn-primary btn-rounded">Search</button>

</form>

</div>

<!-- Select Field Code -->

<div class="form-group">

<label class="col-form-label">Type of Bill</label>

<select name="type_of_bill" class="custom-select">

<option>Open this select menu</option>

<option value="1" <?php if (!(strcmp("1", $rowCus['type_of_bill']))) {

echo "selected=\"selected\"";

} ?>>One</option>

<option value="2" <?php if (!(strcmp("2", $rowCus['type_of_bill']))) {

echo "selected=\"selected\"";

} ?>>Two</option>

<option value="3" <?php if (!(strcmp("3", $rowCus['type_of_bill']))) {

echo "selected=\"selected\"";

} ?>>Three</option>

</select>

</div>

<!-- Text Field Code -->

<div class="form-group">

<label for="example-text-input" class="col-form-label">XO No.</label>

<input name="xo_no" class="form-control" type="text" value="<?php echo $rowCus['xo_no']; ?>" id="example-text-input" required>

</div>