如何知道选择哪个选项PHP

Hello i have a selection and i have some options in it generated by a date array function in php but i want to know which one is selected so when i use it after i can check which one is selected so i can perform actions on it

<select>

    <?php
    function getDays( $year, $startMonth = 1, $startDay = 1, $dayOfWeek = 'monday' ) {
        $start = new DateTime( sprintf( '%04d-%02d-%02d', $year, $startMonth, $startDay ) );
        $start->modify( $dayOfWeek );
        $end = new DateTime( sprintf( '%04d-12-31', $year ) );
        $end->modify( '+1 day' );
        $interval = new DateInterval( 'P1W' );
        $period = new DatePeriod( $start, $interval, $end );

        foreach ( $period as $dt ) {

            echo "<option value=";
            echo $dt->format( "d/m/Y" );
            echo '">';

        echo $dt->format( "d/m/Y" );
        echo "</option>";


    }
    }

    getDays( 2016, 2, 12, 'monday' );
    ?>
</select> 

<?php

(isset($_POST["company"])) ? $company = $_POST["company"] : $company=1;

?>

<form>
<select id="company" name="company">
<option <?php if ($company == 1 ) echo 'selected' ; ?> value="1">Apple</option>
<option <?php if ($company == 2 ) echo 'selected' ; ?> value="2">Samsung</option>
<option <?php if ($company == 3 ) echo 'selected' ; ?> value="3">HTC</option>
</select>
</form>