How to display array value to dropdown list using PHP?

I want to display this array value in dropdown using PHP with output like this 10:00 AM to 10:30 AM. The array below is the output of slots. I want to display start time and end time per list in dropdown.

$slots = getTimeSlot(30, ’10:00′, ’13:00′);

Array
(
    [1] => Array
        (
            [slot_start_time] => 10:00
            [slot_end_time] => 10:30
        )

    [2] => Array
        (
            [slot_start_time] => 10:30
            [slot_end_time] => 11:00
        )

    [3] => Array
        (
            [slot_start_time] => 11:00
            [slot_end_time] => 11:30
        )

    [4] => Array
        (
            [slot_start_time] => 11:30
            [slot_end_time] => 12:00
        )

    [5] => Array
        (
            [slot_start_time] => 12:00
            [slot_end_time] => 12:30
        )

    [6] => Array
        (
            [slot_start_time] => 12:30
            [slot_end_time] => 13:00
        )

)
<select name="time" id="time">
    <option value=""></option>
</select>