I have problem placing a button below a thumbnail in bootstrap.
This image below shows three thumbnails with a button below it. The buttons are not vertically aligned because of the text that appears between the three different thumbnails and buttons are having different lengths.
Here is my code: 
<div class="col-md-3">
    <div class="thumbnail" style="height: 400px;">
        <img style="width: 200px; height: 200px;" src="<?php echo base_url();?>assets/user_file/product/<?php echo $row->foto; ?>">
        <div class="caption">
            <center>
                <h3><?php echo $row->nama_prod; ?></h3>
                <strong><p>Rp.<?php echo $row->harga; ?>.-</p></strong>
                <a href="<?php echo base_url()?>/index.php/pesanan/pesan?id_product=<?php echo $row->id_product?>" class="btn btn-success"> Pesan</a>
            </center>
        </div>
    </div>
</div>
How could I fix this?